Colonoscopy, Colorectal Cancer Screening, and Related Procedures

Number: 0516

Table Of Contents

Policy

Scope of Policy

This Clinical Policy Bulletin addresses colonoscopy, colorectal cancer screening, and related procedures.

1. Medical Necessity

   1. Routine Screening

      Aetna considers any of the following colorectal cancer (CRC) screening tests medically necessary preventive services for average-riskFootnote1* members aged 45 years and older when these tests are recommended by their physician:

      1. Colonoscopy (every 10 years); or
      2. Computed tomography (CT) colonography (virtual colonoscopy) (every 5 years); or
      3. Fecal immunochemical test (FIT) or guaiac-based fecal occult blood testing (FOBT) (every year); or
      4. Flexible sigmoidoscopy (every 5 years); or
      5. Flexible sigmoidoscopy (every 10 years) when combined with an annual FIT or FOBT; or
      6. Stool DNA (FIT-DNA, Cologuard, Cologuard Plus) (every 1 to 3 years).

      Footnote1*Note: The U.S. Preventive Services Task Force (USPSTF, 2021) defines average risk as "no prior diagnosis of colorectal cancer, adenomatous polyps, or inflammatory bowel disease; no personal diagnosis or family history of known genetic disorders that predispose them to a high lifetime risk of colorectal cancer [such as Lynch syndrome or familial adenomatous polyposis]."

      Note: The U.S. Preventive Services Task Force (USPSTF) guidelines apply to routine screening. The USPSTF guidelines have no A or B recommendations for high-risk screening. The USPSTF guidelines indicate that age is one of the most significant risk factors for CRC. While other risk factors such as gender, race/ethnicity, and family history exist, all adults aged 45 to 75 should be offered screening, regardless of the presence of these additional risk factors. For adults aged 76 to 85, the USPSTF recommends that healthcare providers selectively offer CRC screening, as research suggests that the overall benefit for this age group is limited. Clinicians should take into account the individual's overall health, prior screening history, and personal preferences when making decisions about screening.

   2. High-Risk Testing

      Aetna considers colorectal cancer (CRC) testing with sigmoidoscopyor colonoscopy as frequently as every 2 years medically necessary for members with any of the following high-risk factors for CRC:

      1. A first-degree relative (sibling, parent, child) who has had CRC or adenomatous polyps (screening is considered medically necessary beginning at age 40 years, or 10 years younger than the earliest diagnosis in their family, whichever comes first); or
      2. Family history of familial adenomatous polyposis (screening is considered medically necessary beginning at puberty); or
      3. Family history of hereditary non-polyposis CRC (HNPCC) (screening is considered medically necessary beginning at age 20 years); or
      4. Family history of MYH-associated polyposis in siblings (screening is considered medically necessary beginning at age 25 years); or
      5. Diagnosis of Cowden syndrome (screening is considered medically necessary beginning at age 35 years).

      Aetna considers annual FOBT, alone or in conjunction with sigmoidoscopy, medically necessary for testing members with any of the above risk factors for CRC.

   3. Surveillance

      Aetna considers colorectal cancer (CRC) surveillance with colonoscopy or flexible sigmoidoscopy medically necessary as frequently as every year for members who meet any of the following criteria:

      1. Member has inflammatory bowel disease (including ulcerative colitis or Crohn's disease) (CRC surveillance as frequently as every year); or
      2. Personal history of adenomatous polyps (as frequently as every 2 years); or
      3. Personal history of CRC (as frequently as every year).

      Aetna considers annual FOBT, alone or in conjunction with sigmoidoscopy, medically necessary for surveillance of CRC.

      Note: Providers may be required to submit photographs of mucosal abnormalities seen on colonoscopy.

   4. Diagnostic Testing

      Aetna considers diagnostic testing with FOBT, colonoscopy, and/or flexible sigmoidoscopy medically necessary for evaluation of members with signs or symptoms of CRC or other gastrointestinal (GI) diseases. For diagnostic esophagogastroduodenoscopy (EGD)/upper endoscopy, see CPB 0738 - Upper Gastrointestinal Endoscopy and Gastrointestinal Biopsy.

   5. Biopsy of the Lower Gastrointestinal Tract

      Aetna considers biopsy of the lower gastrointestinal tract medically necessary for the following indications:

      1. Microscopic colitis: 8 or more biopsies in persons with symptoms suggestive of microscopic colitis (e.g., diarrhea and/or functional abdominal pain) (2 or more from the ascending, transverse, descending, and sigmoid colon);
      2. Inflammatory bowel disease, diagnosis: 2 or more biopsies from 5 different locations, including the ileum and rectum;
      3. Inflammatory bowel disease, screening for dysplasia: targeted biopsies, plus:
         
         
         1. Pancolitis: biopsies from the 4 quadrants each 10 cm;
         2. Segmental colitis: biopsies from the 4 quadrants each 10 cm limited to involved areas in previous examinations;
      4. Pouchitis: multiple biopsies from the pouch and afferent loop;
      5. Colonic polyps: biopsies of polyps that cannot be removed;
      6. Acute graft-versus-host disease (aGVHD):
         
         
         1. Flexible sigmoidoscopy: 4 or more biopsies from the rectum/sigmoid and 4 or more biopsies from the left colon;
         2. Ileocolonoscopy: 4 or more biopsies from the terminal ileum, ascending colon, transverse colon, descending colon, and rectum/sigmoid colon.

2. Not Medically Necessary

   Aetna considers the following tests and indications not medically necessary (not an all-inclusive list):

   1. Double contrast barium enema (DCBE) for routine CRC screening, high-risk testing, surveillance, and/or diagnostic testing due to its inferior diagnostic performance compared with colonoscopy and CT colonography;
   2. Routine CRC screening for members 85 years of age or older unless life expectancy is greater than or equal to 10 years. Note: The 2021 USPSTF guidelines "conclude that screening in adults aged 76 to 85 years should be an individual decision (C recommendation) and screening should be discontinued after age 85 years".

3. Experimental, Investigational, or Unproven

   1. Colorectal Cancer Screening

      Aetna considers colorectal cancer screening with any of the following methods experimental, investigational, or unproven because the effectiveness of these approaches has not been established:
      

      1. Artificial intelligence-aided colonoscopy (including computer-aided colonoscopy)
      2. Blood-based protein biomarkers (e.g., BeScreened-CRC, Beacon Biomedical, Inc.)
      3. Capsule endoscopy
      4. CD3 immuno-staining
      5. Chromoendoscopy or narrow-band imaging optical colonoscopy
      6. Colon AiQ
      7. Fecal volatile organic compounds
      8. Full-spectrum endoscopy (FUSE) colonoscopy
      9. Guardant Shield Test
      10. Methylated Septin 9 (ColoVantage, Epi proColon)
      11. MicroRNAs
      12. Performance of multiple screening strategies simultaneously in the same individual (e.g., virtual colonoscopy screening every 5 years plus stool DNA testing every 3 years)
      13. Plasma/serum biomarkers (C-reactive protein, complement C3a anaphylatoxin, plasma GATA5 and SFRP2 methylation, serum CD26 (sCD26), serum matrix metalloproteinase-7 (MMP-7), and tissue inhibitor of metalloproteinases (TIMP-1))
      14. PolypDx (Atlantic DiagnosticLaboratories, LLC, Metabolomic Technologies Inc.)
      15. Screening beginning at earlier than standard recommended ages for persons at increased risk due to smoking or obesity
      16. SimpliPro Colon Test
      17. Stool-based protein biomarkers
      18. Stool molecular genetic tests other than Cologuard (e.g., ColoCaller Test, ColoSense multi-target stool RNA test, ColoSure, PreGen-Plus)
      19. Whole-blood DNA methylation markers.
          

   2. Anal Pap Smear

      Aetna considers screening for anal cytological abnormalities (anal Pap smear) or for anal human papilloma virus (HPV) infection experimental, investigational, or unproven because of the lack of evidence that such screening improves clinical outcomes.

   3. Drug-Coated Balloon

      Aetna considers drug-coated balloon experimental, investigational, or unproven for the treatment of colonic strictures because the effectiveness of this approach has not been established.

   4. Full-thickness Resection Device (FTRD)

      Aetna considers the full-thickness resection device (FTRD) experimental, investigational, or unproven for endoscopic resection of appendiceal polyp.

4. Related Policies

   • CPB 0140 - Genetic Testing
   • CPB 0352 - Tumor Markers
   • CPB 0535 - Virtual Gastrointestinal Endoscopy
   • CPB 0588 - Capsule Endoscopy
   • CPB 0717 - Analysis of Volatile Organic Compounds
   • CPB 0738 - Upper Gastrointestinal Endoscopy and Gastrointestinal Biopsy
   • CPB 0783 - In Vivo Analysis of Colorectal Polyps and Crohn's Disease

Background

Colorectal cancer (CRC) is a term used to describe cancer that develops in the colon or rectum. CRC is the third most commonly diagnosed cancer among persons in the United States. The 5-year survival rate of CRC detected in early states is 90%, but the 5-year survival rate is only 8% for those diagnosed after the cancer has metastasized. Almost 90% of CRC cases are found in persons age 50 and older.

CRC screening refers to the process of looking for cancer in people who have no symptoms of the disease. Screening tests may identify cancers at an early and potentially more treatable stage. Testing may also detect precancerous abnormal growths (e.g., polyps) which can be removed before becoming malignant.

In 2008, the American Cancer Society (ACS) (Levin et al., 2008) recommended the following testing options for the early detection of adenomatous polyps and cancer for asymptomatic adults aged 50 years and older:

1. Tests that detect adenomatous polyps and cancer:

   1. Colonoscopy every 10 years; or
   2. Computed tomographic (CT) colonography every 5 years; or
   3. Double-contrast barium enema (DCBE) every 5 years; or
   4. Flexible sigmoidoscopy every 5 years;

2. Tests that primarily detect cancer:

   1. Annual fecal immunochemical test (FIT) with high test sensitivity for cancer; or
   2. Annual guaiac-based fecal occult blood test (FOBT) with high sensitivity for cancer; or
   3. Stool DNA test with high sensitivity for cancer, interval uncertain.

A 2012 guidance statement from the American College of Physicians on "Screening for colorectal cancer" (Qaseem et al., 2012) stated that “The screening interval for average-risk adults older than 50 years is 10 years for colonoscopy; 5 years for flexible sigmoidoscopy, double-contrast barium enema (DCBE), and computed tomography colonography (CTC); annually for guaiac-based fecal occult blood test (gFOBT) and immunochemical-based fecal occult blood test (iFOBT); and uncertain for stool DNA (sDNA)”. 

The USPSTF (2016) found convincing evidence that screening for CRC in adults aged 50 to 75 years reduces CRC mortality. The USPSTF found no head-to-head studies demonstrating that any of the screening strategies it considered are more effective than others, although the tests have varying levels of evidence supporting their effectiveness, as well as different strengths and limitations:

• Colonoscopy every 10 years
• CT colonography every 5 years
• Flexible sigmoidoscopy every 5 years
• Flexible sigmoidoscopy every 10 years plus fecal immuohistochemical test (FIT) every year
• Guaiac-based fecal occult blood test (gFOBT) every year
• FIT test every year
• Stool DNA (FIT-DNA) every one or three years.

1. average‐risk adults in good health with a life expectancy of more than 10 years continue CRC screening through the age of 75 years;
2. clinicians individualize CRC screening decisions for individuals aged 76 through 85 years based on patient preferences, life expectancy, health status, and prior screening history; and
3. clinicians discourage individuals older than 85 years from continuing CRC screening.

On the basis of the strength of the evidence and on the judgment of an overall preponderance of benefit, the recommendation for regular screening in adults aged 50 years and older was designated by the American Cancer Society (ACS) as a “strong” recommendation (Wolf et al., 2018). The recommendation to begin screening at age 45 years was based on disease burden, results from microsimulation modeling, and the reasonable expectation that screening will perform similarly in adults aged 45 to 49 years as in persons for whom screening is currently recommended. However, the long‐standing recommendation to initiate CRC screening at age 50 years means that there are limited data on screening outcomes in adults aged 45 to 49 years. Because of differences in the type and quality of evidence for screening in adults younger than 50 years, the recommendation to start screening at age 45 years had been designated by the ACS as “qualified.”

In 2018, several medical organizations recommended against CRC screening for asymptomatic patients with a life expectancy of less than 10 years and no personal or family history of colorectal neoplasia. The American College of Surgeons issued this guidance, as did the Society of General Internal Medicine, which also advises against cancer screening in adults with a life expectancy under 10 years. Additionally, the AMDA, the Society for Post-Acute and Long-Term Care Medicine, supports this recommendation, emphasizing that CRC screening is not warranted in individuals with a similar life expectancy (Choosing Wisely, 2018a, 2018b, 2018c).

In 2021, the USPSTF updated its recommendation for CRC screening, lowering the starting age from 50 to 45 years and extending the recommended screening age range to 45 to 75 years. The USPSTF continues to advocate for selective screening of adults aged 76 to 85 years, noting that the overall benefit of screening this age group is minimal. Specifically, the USPSTF recommends routine screening for all adults aged 50 to 75 years (A recommendation) and for adults aged 45 to 49 years (B recommendation), while suggesting that clinicians selectively offer screening for those aged 76 to 85 years based on individual health, prior screening history, and patient preferences (C recommendation). In adults 86 years or older, evidence on benefits and harms of colorectal cancer screening is lacking, and competing causes of mortality likely preclude any survival benefit that would outweigh the harms of screening. Various screening tests are available, and clinicians and patients should consider factors such as screening frequency, location (home or office), method (stool-based or direct visualization), bowel preparation, anesthesia or sedation needs, and follow-up for abnormal results when choosing the most suitable test. Recommended screening options include the high-sensitivity guaiac fecal occult blood test (HSgFOBT) or fecal immunochemical test (FIT) annually, stool DNA-FIT every 1 to 3 years, computed tomography (CT) colonography every 5 years, flexible sigmoidoscopy every 5 years or 10 years when combined with annual FIT, and colonoscopy every 10 years. The USPSTF does not recommend the use of double-contrast barium enema (DCBE) for screening.

The 2024 American Cancer Society guideline for CRC screening recommends that individuals at average risk for CRC begin regular screening at age 45. This screening can be conducted using either a sensitive stool-based test that detects signs of cancer or through a visual examination of the colon and rectum. Those in good health with a life expectancy of more than 10 years should continue regular screenings until age 75. For individuals aged 76 to 85, the decision to undergo screening should be guided by personal preferences, life expectancy, overall health, and previous screening history. People over the age of 85 are advised to discontinue CRC screening. Individuals are considered to be at average risk for screening if they do not have a personal history of CRC or certain types of polyps, a family history of CRC, a personal history of inflammatory bowel disease (such as ulcerative colitis or Crohn’s disease), a confirmed or suspected hereditary CRC syndrome (like familial adenomatous polyposis or Lynch syndrome), or a personal history of radiation treatment to the abdomen or pelvic area for prior cancer.

The American Cancer Society (Wolf et al., 2026) has updated its clinical practice guideline for colorectal cancer screening, specifically targeting average-risk, asymptomatic adults aged 45 years and older. This guideline is applicable to individuals without a personal history of colorectal cancer, adenomatous or sessile serrated polyps, inflammatory bowel disease, hereditary colorectal cancer syndromes, significant family history, or prior abdominal or pelvic radiation. It reaffirms the initiation of screening at age 45, recommends continuation through age 75 for individuals with a life expectancy exceeding 10 years, supports individualized decision-making for those aged 76 to 85, and advises against screening after age 85. Preferred screening modalities include annual high-sensitivity fecal immunochemical testing or high-sensitivity guaiac-based fecal occult blood testing, multitarget stool DNA testing every 3 years, multitarget stool RNA (mt-sRNA) testing every 3 years, colonoscopy every 10 years, computed tomography colonography every 5 years, and flexible sigmoidoscopy every 5 years. The mt-sRNA test has shown a sensitivity of 94.4% for colorectal cancer and 45.9% for advanced adenomas, with a specificity of 85.5% among individuals without advanced colorectal neoplasia, thus being included as a preferred stool-based option. However, the guideline acknowledges certain limitations, such as reliance on a single prospective validation study, the absence of randomized trials demonstrating reductions in colorectal cancer incidence or mortality, limited data on real-world adherence across repeated screening rounds, uncertainty regarding the optimal screening interval, and lower specificity compared to some other stool-based tests, which may increase the burden of follow-up colonoscopy. Blood-based cell-free DNA tests exhibit lower sensitivity for advanced precancerous lesions (12.5%–13.2%) and stage I cancers (57.1%–64.7%), with modeling studies indicating smaller reductions in colorectal cancer incidence and mortality compared to preferred stool-based and structural examinations; therefore, blood-based tests are recommended only for individuals who decline or do not complete preferred screening tests. The guideline emphasizes that any positive non-colonoscopy screening result necessitates timely follow-up colonoscopy, ideally within 6 months, to complete the screening process. The recommendation to initiate screening at age 45 is classified as a qualified recommendation, while regular screening for adults aged 50 and older is designated as a strong recommendation. Additionally, the guideline notes that the most recent US Preventive Services Task Force colorectal cancer screening recommendations published in 2021 did not include mt-sRNA or blood-based tests, as these technologies had not yet received FDA approval, which has implications for coverage under policies linked to USPSTF grade A or B recommendations.

The available options for CRC screening include fecal immunohistochemical test (FIT) or guaiac-based fecal occult blood testing (FOBT), flexible sigmoidoscopy, stool DNA, colonoscopy, and computed tomographic (CT) colonography (virtual colonoscopy).

No current guidelines of leading medical professional organizations or Federal public health agencies recommend routine upper endoscopy screening of asymptomatic persons. Although screening upper endoscopy has been performed in conjunction with screening colonoscopy, there is no evidence-based support for this practice.

Anal Pap Smear and Anal Dysplasia Screening

The Centers for Disease Control and Prevention (CDC) advises against routine testing for anal cytological abnormalities or anal human papillomavirus (HPV) infection, citing the need for more data on the reliability of screening methods, treatment safety and efficacy, and programmatic factors (Workowski and Berman, 2006). Similarly, the Ontario Health Technology Advisory Committee (OHTAC) conducted a systematic review of the evidence surrounding anal dysplasia screening and concluded in 2007 that screening for high-risk individuals is not recommended at this time. This decision is based on the low specificity of cytological screening, insufficient evidence supporting the effectiveness of current treatments for precancerous lesions, high recurrence rates, and a lack of evidence indicating that cytological screening reduces the risk of developing anal cancer.

In a prospective cohort study, Schofield and colleagues (2016) sought to establish the feasibility and acceptability of anal screening among men who have sex with men (MSM). Subjects were known HIV-positive and negative MSM who have anoreceptive intercourse. The intervention included anal screening with HPV testing, liquid-based cytology, and high-resolution anoscopy (HRA) with biopsy of anoscopic abnormalities. Participants completed questionnaires at baseline and at 6 months. Anal HPV was highly prevalent in MSM (HIV-positive, 88%; and HIV-negative, 78%). Despite the high prevalence of cytological abnormality in both HIV-positive (46.2%) and HIV-negative (35.0%) MSM, almost 50% of anal intraepithelial neoplasia (AIN) of all grades were associated with negative cytology. Anoscopically directed biopsies detected AIN3 or worse (AIN3+) in 14 of 203 (6.9%) of HIV-positive MSM and 3 of 81 (3.7%) HIV-negative MSM. The corresponding prevalence of AIN2+ was 26.6% and 20.9%, respectively; 1 case of AIN3 was detected at the second visit. Screening was considered to be highly acceptable by participants. The authors concluded that the high prevalence of high-risk HPV and the frequency of false-negative cytology in this study suggested that HRA would have the most clinical utility as a primary screening tool for anal cancer in a high-risk group. The prevalence of AIN3+ in HIV-positive MSM provided support for a policy of screening this group, but the high prevalence of lower-grade lesions that do not warrant immediate treatment and the limitations of treating high-grade lesions require careful consideration in terms of a screening policy.

In a review on “Anal cancer and intraepithelial neoplasia screening,” Leeds and Fang (2016) focused on the early diagnosis of anal cancer and its precursor lesions through routine screening. A number of risk-stratification strategies as well as screening techniques have been suggested, and currently, little consensus exists among national societies. Much of the current clinical rationale for the prevention of anal cancer derives from the similar tumor biology of cervical cancer and the successful use of routine screening to identify cervical cancer and its precursors early in the disease process. It is thought that such a strategy of identifying early anal intraepithelial neoplasia will reduce the incidence of invasive anal cancer. The low prevalence of anal cancer in the general population prevents the use of routine screening. However, routine screening of selected populations has been shown to be a more promising strategy. Potential screening modalities include digital anorectal exam, anal Papanicolaou testing, HPV co-testing, and HRA. The authors concluded that additional research associating high-grade dysplasia treatment with anal cancer prevention, as well as direct comparisons of screening regimens, is needed to develop further anal cancer screening recommendations.

Artificial Intelligence-Aided Colonoscopy for Colorectal Cancer Screening

Brown et al. (2022) noted that artificial intelligence (AI)-based computer-aided polyp detection (CADe) systems are intended to address the issue of missed polyps during colonoscopy. The effect of CADe during screening and surveillance colonoscopy has not previously been studied in a U.S. population. In a prospective, single-blind, multi-center, randomized tandem colonoscopy study, these researchers examined the effectiveness of a deep-learning (DL)-based CADe system (EndoScreener, Shanghai Wision AI, China). Participants were enrolled across four U.S. academic medical centers from 2019 through 2020. Patients presenting for CRC screening or surveillance were randomized to CADe colonoscopy first or high-definition white light (HDWL) colonoscopy first, followed immediately by the other procedure in tandem fashion by the same endoscopist. The primary outcome was adenoma miss rate (AMR), and secondary outcomes included sessile serrated lesion (SSL) miss rate and adenomas per colonoscopy (APC). A total of 232 patients entered the study, with 116 patients randomized to undergo CADe colonoscopy first and 116 patients randomized to undergo HDWL colonoscopy first. After the exclusion of nine patients, the study cohort included 223 patients. AMR was lower in the CADe-first group compared with the HDWL-first group (20.12% [34/169] versus 31.25% [45/144]; OR, 1.8048; 95% CI: 1.0780 to 3.0217; p = 0.0247). SSL miss rate was lower in the CADe-first group (7.14% [1/14]) versus the HDWL-first group (42.11% [8/19]; p = 0.0482). First-pass APC was higher in the CADe-first group (1.19 (SD), 2.03 versus 0.90 (SD), 1.55; p = 0.0323). First-pass ADR was 50.44% in the CADe-first group and 43.64% in the HDWL-first group (p = 0.3091). The authors concluded that in this multi-center tandem colonoscopy RCT, they showed a decrease in AMR and SSL miss rate and an increase in first-pass APC with the use of a CADe system when compared with HDWL colonoscopy alone. These researchers stated that CADe has the potential to decrease inter-provider variability in colonoscopy quality by reducing AMR, even in experienced providers.

The authors stated that this study had several drawbacks. First, this trial was not powered to detect a difference in ADR. Second, the tandem colonoscopy design used in this trial showed important insights regarding CADe performance; however, it was somewhat limited in terms of generalizability to the real-world clinical setting. Endoscopists could not be blinded to a patient’s group assignment while conducting each withdrawal. It was possible that endoscopist performance was influenced by being observed or that endoscopists who participated for the length of the study became over-reliant on CADe during withdrawal, leading to an over-estimation or under-estimation of CADe performance. However, these effects should generally have been balanced across both randomization groups. Third, this trial only included experienced endoscopists with a high baseline ADR at U.S. academic medical centers. It was less clear how CADe-assisted colonoscopy would affect endoscopy performance for trainees, junior endoscopists, and in community settings. Some studies suggested the most benefit for CADe for endoscopists with limited experience or high procedure volume and for patients who present with a high polyp burden. Fourth, this study employed a second monitor adjacent to the primary endoscopy monitor, similar to other early trials. However, recent studies, including the authors’ previous tandem colonoscopy study, had used a single-monitor setup. Although a dual-monitor setup may be less burdensome if the latency of the CADe system is above a detectable visible threshold, it may also have negative effects on endoscopist gaze patterns. These investigators suspected a single-monitor setup may be preferred in the long run as it allows for easier integration of the technology.

Mehta et al. (2023) stated that as AI-assisted diagnosis gained immense popularity, it is imperative to consider its use and effectiveness in the early diagnosis of CRC, responsible for over 1.8 million cases and 881,000 deaths globally, as reported in 2018. Improved adenoma detection rate, as well as better characterizations of polyps, are significant advantages of AIC. This systematic review examined the effectiveness of AI-assisted colonoscopy (AIC) in the early diagnosis of CRC as compared to conventional colonoscopy. Electronic databases such as PubMed/Medline, SCOPUS, and Web of Science (WOS) were reviewed for original studies (RCTs, observational studies), systematic reviews, and meta-analyses between 2017 and 2022 employing MESH terminology in a broad search strategy. All searches were carried out and analyzed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) methodology and were conducted in November 2022. A data extraction form based on the Cochrane Consumers and Communication Review Group's extraction template for quality assessment and evidence synthesis was used for data extraction. All included studies were considered for bias and ethical criteria and provided valuable evidence to answer the research question. The database search identified 218 studies, including 87 from PubMed, 60 from SCOPUS, and 71 from Web of Science databases. The retrieved studies from the databases were imported to Rayyan software, and a duplicate article check was performed; all duplicate articles were removed after careful evaluation of the data. The abstract and full-text screening was performed in accordance with the following eligibility criteria: STROBE for observational studies; PRISMA for review articles; ENTREQ for narrative studies; and modified JADAD for RCTs. This yielded 15 studies that met the requirements for the systematic review and were finally included in the review. The authors concluded that AIC was a safe, highly effective screening tool that can increase the detection rate of adenomas and polyps, resulting in early diagnosis of CRC in adults when compared to conventional colonoscopy. Moreover, these researchers stated that the findings of this systematic review prompted further large-scale research to examine the effectiveness in accordance with gender, race, and socioeconomic status, as well as its influence on prognosis and survival rate.

Shah et al. (2023) noted that multiple computer-aided techniques utilizing AI have been created to improve the detection of polyps during colonoscopy, thus reducing the incidence of CRC. While adenoma detection rates (ADR) and polyp detection rates (PDR) are important colonoscopy quality indicators, AMR may better quantify missed lesions, which can ultimately lead to interval CRC. In a systematic review and meta-analysis, these investigators examined the effectiveness of computer-aided colonoscopy (CAC) with respect to AMR, ADR, and PDR in RCTs. These researchers carried out a comprehensive, systematic literature search across multiple databases in September 2022 to identify RCTs that compared CAC with traditional colonoscopy. Primary outcomes were AMR, ADR, and PDR. A total of 14 studies totaling 10,928 patients were included in the final analysis. There was a 65% reduction in the adenoma miss rate with CAC (OR, 0.35; 95% CI: 0.25 to 0.49, p < 0.001, I² = 50%). There was a 78% reduction in the sessile serrated lesion miss rate with CAC (OR, 0.22; 95% CI: 0.08 to 0.65, p < 0.01, I² = 0%). There was a 52% increase in ADR in the CAC group compared with the control group (OR, 1.52; 95% CI: 1.39 to 1.67, p = 0.04, I² = 47%). There was a 93% increase in the number of adenomas greater than 10 mm detected per colonoscopy with CAC (OR, 1.93; 95% CI: 1.18 to 3.16, p < 0.01, I² = 0%). The authors concluded that the findings of the present study showed the promise of CAC in improving AMR, ADR, and PDR across a spectrum of size and morphological lesion characteristics.

Spadaccini et al. (2023) stated that CRC is the third most common cancer worldwide, with the highest incidence reported in high-income countries. However, because of the slow progression of neoplastic precursors, along with the opportunity for their endoscopic detection and resection, a well-designed endoscopic screening program is expected to strongly decrease CRC incidence and mortality. In this regard, the quality of colonoscopy has been clearly related to the risk of post-colonoscopy CRC. Recently, the development of AI applications in the medical field has been growing in interest. Through machine learning processes, and, more recently, DL, if a very high number of learning samples are available, AI systems may automatically extract specific features from endoscopic images/videos without human intervention, helping the endoscopists in different aspects of their daily practice. The aim of this review is to summarize the current knowledge on AI-aided endoscopy and to outline its potential role in colorectal cancer prevention. These researchers stated that preliminary data on both computer-aided characterization (CADx) systems as well as AI-assisted quality-control systems are promising; however, the lack of high-quality clinical studies prevents any reliable conclusion. Therefore, such studies should be considered a priority in future research agendas. The steps to be carried out are still many; however, the path does not appear so steep anymore.

Mansur et al. (2023) noted that AI is a branch of computer science that employs optimization, probabilistic, and statistical approaches to analyze and make predictions based on a vast amount of data. In recent years, AI has revolutionized the field of oncology and spearheaded novel approaches in the management of various cancers, including CRC. Notably, the use of AI to diagnose, prognosticate, and predict response to therapy in CRC is gaining traction and proving to be promising. There have also been several advancements in AI technologies to help predict metastases in CRC and in CAD systems to improve miss rates for colorectal neoplasia. These investigators stated that while promising, the use of AI in clinical medicine is still at an early stage. One of the biggest drawbacks with AI is that models tend to be limited by the amount and quality of available labeled data for model development and validation. The generalizability of the models is also based on the type of data used in training. Large datasets that are ethnographically diverse will be needed to ensure that models can be applied for decision-making in diverse patient populations. In addition, there is a need to establish ethical guidelines before models can ever be widely employed to ensure their appropriate use and access. Another issue with the clinical application of AI and machine learning (ML) is the “black box” problem, in which researchers are able to see the inputs and outputs of a model, but not the variables that are used by the model to generate those outputs. More efforts are needed to make the algorithms, especially DL algorithms, interpretable to clinicians and to allow streamlining of data pre-processing. Furthermore, most of the studies have a retrospective design, and more evidence on the effectiveness of AI is needed from prospective, multi-center studies. Finally, standards need to be established for the required accuracy rates to ensure the safe use and legality of AI technology. Efforts are needed to ensure that sensitive data are kept confidential. Nonetheless, the potential of AI in medicine, and specifically CRC, is promising. The authors concluded that while there remain challenges to overcome with regards to the generalizability, validation, and clinical application of these technologies, future developments may eventually result in improved outcomes and a paradigm shift in how patients with suspected or diagnosed CRC are cared for.

Sekiguchi et al. (2025) stated that ensuring the high quality of colonoscopies in CRC screening is crucial in reducing CRC. Recently, computer-aided detection systems (CADe) that employ AI have attracted much attention as potentially useful tools for improving lesion detection in colonoscopy. However, evidence on the effectiveness of CADe in CRC screening is lacking. These investigators have planned a multi-national, multi-center RCT in the Asia-Pacific region to examine if colonoscopy with CADe (test method) will yield higher lesion detection (primary endpoint: adenoma detection rate) than colonoscopy without CADe (standard method) in CRC screening populations. The study will include 1,400 participants aged 50 to 79 years who are due to undergo colonoscopy for CRC screening, whether as a primary screening colonoscopy or following a positive FIT. If the effectiveness of CADe is proven from this study, the use of CADe in colonoscopy for CRC screening will become standard, resulting in improved CRC screening.

Endo et al. (2025) noted that CT colonography is increasingly recognized as a valuable modality for diagnosing colorectal lesions; however, the interpretation workload remains challenging for physicians. Deep learning (DL)-based AI algorithms have been used for imaging diagnoses. These researchers examined the sensitivity of neoplastic lesions in CT colonography images. Lesion location and size were examined during colonoscopy, and a large-scale database including a dataset for AI learning and external validation was created. The DICOM data used as training data and internal validation data (total 453 patients) for this study were CRC screening test data from two multi-center joint trials carried out in Japan and data from two centers. External validation data (137 patients) were from two other centers. Lesions were categorized into ≥ 6 mm, 6 to 10 mm, and ≥ 10 mm. During this study, these investigators adopted a neural network structure that was designed based on the faster R-CNNs to detect colorectal lesions. The sensitivity of detecting colorectal lesions was verified when one and two positions were integrated. Internal validation yielded sensitivity of 0.815, 0.738, and 0.883 for lesions ≥ 6 mm, 6 to 10 mm, and ≥ 10 mm, respectively, with a false lesion limit of three. Two external validations produced rates of 0.705 and 0.707, 0.575 and 0.573, and 0.760 and 0.779 for each lesion category. Combining two positions for each patient in calculating the sensitivity resulted in significantly improved rates for each lesion category. The authors concluded that the sensitivity of CT colonography images using the AI algorithm was improved by integrating evaluations in two positions. These researchers stated that in the future, validation experiments involving radiologists who can interpret images as well as AI to determine the auxiliary diagnosis can reduce the workload of physicians.

The authors stated that this study had several drawbacks. First, these investigators were unable to assess the specificity due to the absence of negative cases in the external validation dataset. In future research, these researchers believe it is necessary to carry out validation using a large-scale dataset that includes negative cases and to examine the specificity more accurately along with the sensitivity. Second, this trial did not validate how physicians interpreted the lesions identified by the AI algorithm. The sensitivity of the AI algorithm was evaluated based on its ability to detect lesions that were endoscopically confirmed. In future studies, it will be necessary to carry out evaluations that incorporate physicians' diagnoses to examine the performance of the AI algorithm more accurately. Third, the authors did not examine the threshold value and allowed number of false-positive lesions during the interpretation of the actual images. Fourth, this study did not examine the cost-effectiveness or feasibility of implementing dual-position imaging and diagnosis using AI algorithms in real-world clinical settings. Given the current radiologist shortage, cost and operational considerations are especially important.

Hassan et al. (2025) stated that colonoscopy, a crucial procedure for detecting and removing colorectal polyps, has seen transformative advancements via the use of AI, specifically in CADe and CADx. These tools enhance real-time detection and characterization of lesions, potentially reducing human error and standardizing the quality of colonoscopy across endoscopists. CADe has proven effective in increasing adenoma detection rates, potentially reducing long-term CRC incidence. However, CADe's benefits are accompanied by challenges, such as potentially longer procedure times, increased non-neoplastic polyp resections, and a higher surveillance burden. CADx, while promising in differentiating neoplastic and non-neoplastic diminutive polyps, encounters limitations in accuracy, especially in the proximal colon. Real-world data also showed gaps between trial effectiveness and practical outcomes, emphasizing the need for further research in uncontrolled settings. Moreover, CADx's limited specificity and binary output underscore the necessity for explainable AI to gain endoscopists' trust. The authors examined the benefits, harms, and limitations of AI for colon cancer screening, surveillance, and treatment, focusing on CADe and CADx systems for lesion detection and characterization, respectively, while addressing challenges in integrating these technologies into clinical practice.

Auxiliary Imaging Device

Retrograde imaging/illumination (e.g., Third Eye Retroscope, Third Eye Panoramic Auxiliary Endoscopy System) are imaging devices that have been suggested to provide illumination and continuous retrograde views of the colon. Examples of these devices include, but may not be limited to, the Third Eye Retroscope, which involves the use of a J-shaped catheter that contains an imaging device that can be inserted into the endoscopic working channel. It is intended for single use and is disposable. Another example of these devices is the Third Eye Panoramic device, which can be attached to the distal end of the colonoscope with a flexible clip and provides continuous left-side and right-side views of the colon, displayed simultaneously on three monitors.

Blood-Based Biomarkers for Colorectal Cancer Screening

In a study that compared the performance of serum markers (C-reactive protein, serum CD26 [sCD26], complement C3a anaphylatoxin, and tissue inhibitor of metalloproteinases [TIMP-1]) with stool fecal occult blood tests for the detection of colon cancer and advanced adenomas among patients with known and no known colon disease, at a specificity of 97.7%, the sensitivity of the four serum markers was less than 20% compared with 40% for gFOBT and 66% for iFOBT.

In a meta-analysis, Xing and colleagues (2014) identified the value of serum matrix metalloproteinase-7 (MMP-7) levels for the diagnosis of colorectal cancer (CRC). Through searching the following electronic databases: Cochrane Library (Issue 12, 2014), Web of Science (1945 to 2014), PubMed (1966 to 2014), CINAHL (1982 to 2014), EMBASE (1980 to 2014), and CBM (1982 to 2014), related articles were determined without any language restrictions. Stata statistical software (Version 12.0, Stata Corporation, College Station, TX) was chosen to deal with statistical data. Standard mean difference (SMD) and its corresponding 95% confidence interval (CI) were calculated to clarify the correlation between serum MMP-7 levels and CRC. A total of seven clinical case-control studies that recruited 430 CRC patients and 357 healthy subjects were selected for statistical analysis. The main findings of the meta-analysis showed that the serum MMP-7 level in CRC patients was significantly higher than that in control subjects (SMD = 2.15, 95% CI: 1.46 to 2.84, p < 0.001). Ethnicity-stratified analysis indicated a higher serum MMP-7 level in CRC patients than that of control subjects among Asians and Caucasians (Asians: SMD = 2.83, 95% CI: 1.76 - 3.91, p < 0.001; Caucasians: SMD = 1.06, 95% CI: 0.46 to 1.66, p = 0.001; respectively). The authors concluded that the present meta-analysis indicated that the increased serum level of MMP-7 may be connected with the development of CRC; thus, serum levels of MMP-7 could be an independent biomarker for CRC patients.

Zhang and colleagues (2015) examined GATA5, SFRP2, and ITGA4 methylation in plasma DNA as non-invasive biomarkers for CRC or adenomas. There were 57 CRC patients, 30 adenoma patients, and 47 control patients enrolled in this study. Methylation-specific PCR was used to determine the promoter methylation status of GATA5, SFRP2, and ITGA4 genes in plasma DNA, and their association with clinical outcomes in CRC. The predictive ability of GATA5, SFRP2, and ITGA4 methylation, individually or in combination, to detect CRC or adenomas was further analyzed. Hyper-methylated GATA5 was detected in plasma in 61.4% (35/57) of CRC cases, 43.33% (13/30) of adenoma cases, and 21.28% (10/47) of control cases. The hyper-methylation of SFRP2 was detected in 54.39% (31/57), 40.00% (12/30), and 27.66% (13/47) in plasma samples from CRC, adenomas, and controls, respectively. ITGA4 methylation was detected in 36.84% (21/57) of plasma samples of CRC patients and in 30.00% (9/30) of plasma samples from patients with colorectal adenomas, and the specificity of this individual biomarker was 80.85% (9/47). Moreover, GATA5 methylation in the plasma was significantly correlated with larger tumor size (p = 0.019), differentiation status (p = 0.038), TNM stage (p = 0.008), and lymph node metastasis (p = 0.008). SFRP2 and ITGA4 methylation in plasma significantly correlated with differentiation status (SFRP2, p = 0.012; ITGA4, p = 0.007), TNM stage (SFRP2, p = 0.034; ITGA4, p = 0.021), and lymph node metastasis (SFRP2, p = 0.034; ITGA4, p = 0.021). From the perspective of predictive power and cost-performance, using GATA5 and SFRP2 together as methylation markers seemed the most favorable predictor for CRC (OR = 8.06; 95% CI: 2.54 to 25.5; p < 0.01) and adenomas (OR = 3.35; 95% CI: 1.29 to 8.71; p = 0.012). The authors concluded that a combination of GATA5 and SFRP2 methylation could be promising as a marker for the detection and diagnosis of CRC and adenomas.

Blood-Based Biomarker Panel (ColonSentry) for Colorectal Cancer Screening

Blood-based biomarker panels are tests designed to evaluate gene expression in order to estimate an individual's relative risk of CRC. One such test is ColonSentry, which is thought to enhance patient compliance with colonoscopy screenings. This test measures the expression of seven specific genes: ANXA3, CLEC4D, IL2RB, LMNB1, PRRG4, TNFAIP6, and VNN139.

In February 2012, the New York State Department of Health approved ColonSentry to identify patients at higher risk for colorectal cancer, with the goal of monitoring these individuals and promoting adherence to regular colonoscopy screenings. However, the test has not been shown to effectively detect early-stage cancers, which is the most critical time for screening. Furthermore, its sensitivity (ranging from 61% to 82%) and specificity (ranging from 64% to 77%) were only moderate for colorectal cancer across all stages when evaluated in populations that included a significant number of patients with known CRC.

Blood-Based Cell-Free DNA Tests for Colorectal Cancer Screening

Blood-based cell-free DNA (cfDNA) testing for colorectal cancer (CRC) screening is a non-invasive diagnostic method that examines fragments of DNA present in the bloodstream to identify molecular signatures linked to colorectal cancer or advanced adenomas. This liquid biopsy technique analyzes tumor-derived DNA alterations, including methylation patterns, mutations, and other epigenetic changes, found in plasma.

Colon AiQ

Colon AiQ (Breakthrough Genomics) is a cell-free DNA (cfDNA) methylation-based quantitative PCR assay that evaluates biomarkers such as SEPTIN9, IKZF1, BCAT1, VAV3, and BCAN in plasma. This test utilizes DNA methylation technology to detect small traces of tumor cfDNA in the blood. Results are interpreted through AI-powered computer analysis and reported as the presence or absence of circulating tumor DNA (ctDNA). If a patient receives a positive result indicating that a colorectal cancer (CRC) signal has been detected, it is recommended that they consult with their healthcare provider and pursue further testing, including a colonoscopy.

Colon AiQ has not been granted full Food and Drug Administration (FDA) approval for the use as a CRC screening method.

Guardant Shield

The Guardant Shield is an FDA-approved, non-invasive blood-based screening test designed to detect alterations associated with colorectal cancer (CRC) in individuals aged 45 and older who are at average risk for the disease; it is not intended for those at high risk. A positive result indicates a potential presence of colorectal cancer or advanced adenoma, prompting a referral for colonoscopy evaluation. The test utilizes a multi-modal approach that combines genomics, epigenomics, and proteomics to identify CRC signals in the bloodstream, including circulating tumor DNA (ctDNA) released by tumors. Validation studies have shown a sensitivity of 91% for CRC detection and 20% for advanced adenoma detection, with a specificity of 92% for normal cases. As a laboratory-developed test (LDT), the Guardant Shield is meant to complement existing recommended CRC screening methods rather than replace them.

In the prospective, observational, multicenter ECLIPSE study funded by Guardant Health, Chung et al. (2024) evaluated the performance of a cfDNA blood-based test in average-risk individuals eligible for CRC screening. The study enrolled 22,877 participants aged 45 to 84, of whom 7,861 (76.6%) were evaluable for final analysis. This participant demographic distribution was consistent with the 2020 U.S. Census. The primary outcomes assessed the test's sensitivity for CRC detection and its specificity for advanced neoplasia, which includes CRC and advanced precancerous lesions, compared to screening colonoscopy, while the secondary outcome focused on sensitivity for identifying advanced precancerous lesions. Results showed that 83.1% of participants with CRC detected by colonoscopy had a positive cfDNA test, yielding a sensitivity of 83.1% (95% confidence interval [CI], 72.2 to 90.3) for CRC detection, with sensitivity for stages I, II, or III CRC at 87.5% (95% CI, 75.3 to 94.1) and sensitivity for advanced precancerous lesions at 13.2% (95% CI, 11.3 to 15.3). Among participants without advanced colorectal neoplasia, 89.6% had a negative cfDNA test, resulting in a specificity of 89.6% (95% CI, 88.8 to 90.3) for advanced neoplasia and 89.9% (95% CI, 89.0 to 90.7) for negative colonoscopy results. The study concluded that the Guardant Health cfDNA blood-based test demonstrated 83% sensitivity for CRC, 90% specificity for advanced neoplasia, and 13% sensitivity for advanced precancerous lesions (ECLIPSE ClinicalTrials.gov number, NCT04136002). Chung et al. also noted that CRC is the third most diagnosed cancer in adults in the U.S., with early detection capable of preventing over 90% of CRC-related deaths; however, more than one-third of the screening-eligible population remains not up-to-date with screening despite multiple available tests. They emphasized that blood-based testing could enhance screening adherence, facilitate earlier detection, and reduce CRC-related mortality, highlighting that only 59% of eligible individuals are current with screening. Estimates suggest that adherence to blood-based tests is higher than for stool-based tests or direct visualization methods. The authors called for further evaluation of participant adherence to cfDNA blood-based tests in various clinical settings, as adherence is influenced by factors beyond test availability, and noted that a non-invasive screening strategy requires adherence to both the screening test and follow-up diagnostic colonoscopy for those with positive results. Ongoing studies will explore the screening journey for participants choosing this blood-based test and its implications for follow-up colonoscopy, while future research on health economics and outcomes modeling could assess the impact of this blood-based test on CRC-related outcomes, particularly regarding its proposed three-year screening interval.

Lei et al. (2024) stated that CRC and gastric cancer (GC) rank among the top 5 most common and lethal cancers worldwide. Early detection can significantly reduce mortality rates; however, current clinical screening methods, including invasive endoscopic techniques and non-invasive fecal occult blood tests (FIT), often exhibit low sensitivity and poor patient compliance. Aberrant DNA methylation frequently occurs in tumorigenesis, and cfDNA methylation has shown promise in multi-cancer detection. The researchers developed a non-invasive method for CRC and GC detection using targeted methylation sequencing on 407 plasma samples from patients diagnosed with CRC, GC, and non-cancerous gastrointestinal benign diseases. They identified 40,110 GI cancer-specific markers and developed an integrated model for GI cancer detection and tissue of origin (TOO) prediction, achieving overall sensitivities of 83% and 81.3% at specificities of 81.5% and 80% in the test and validation sets, respectively. The authors concluded that cfDNA methylation signatures are promising tools for early GI cancer detection and non-invasive screening, although further large-scale validation in high-risk populations is needed for cost-effective application.

Henriksen et al. (2024) proposed ctDNA as a tool for minimal residual disease (MRD) assessment. They utilized digital PCR (dPCR) for ctDNA detection in a large CRC cohort to evaluate post-operative risk assessment and serial monitoring. In an observational study involving 851 stage II to III CRC patients treated with curative intent, plasma samples were collected post-operation and periodically for up to 36 months. The study found that both post-operative and serial ctDNA detection were prognostic of recurrence, with a cumulative detection rate of 87% in recurrence patients. The authors concluded that their personalized dPCR approach effectively detected MRD and showed promise for recurrence surveillance, with the ability to adjust sensitivity and specificity for different clinical contexts.

In a randomized study, Coronado et al. (2024) examined if individuals who had not completed a FIT for CRC screening would complete a blood-based testing option if offered one during health encounters. Blood-based screening tests for CRC could add to the total number of people screened for CRC by providing another testing alternative. Study participants were patients aged 45 to 75 years at a large, integrated health system who were offered but did not complete an FIT in the previous 3 to 9 months and were scheduled for a clinical encounter. Participants were randomized (1:1) to be offered a commercially available CRC blood test (Shield, Guardant Health) versus usual care. These investigators compared 3-month CRC screening proportions in the two groups. They randomized 2,026 patients; 2,004 remained eligible following post-randomization exclusions (1,003 to usual care and 1,001 to blood draw offer; mean age: 60 years, 62% women, 80% non-Hispanic white). Of the 1,001 allocated to the blood test group, 924 were recruited following chart-review exclusions; 548 (59.3%) were reached via phone, of which 280 (51.1%) scheduled an appointment with the research team. CRC screening proportions were 17.5 percentage points higher in the blood test group versus usual care (30.5% versus 13.0%; OR 2.94, 95% CI: 2.34 to 3.70; p < 0.001). The authors concluded that among adults who had declined previous CRC screening, the offer of a blood-based screening test boosted CRC screening by 17.5 percentage points over usual care. Moreover, these researchers stated that further investigation is needed on how to balance the favorable adherence with lower advanced adenoma detection compared with other available tests.

Haynes et al. (2025) evaluated the real-world implementation of blood-based colorectal cancer (CRC) screening in two Appalachian primary care clinics, a region with historically low CRC screening rates and high CRC incidence and mortality. The study used a two-phase design: in Phase 1, only standard-of-care (SOC) screening options (colonoscopy and stool-based tests) were offered; in Phase 2, a blood-based test was added as an option alongside SOC. Screening rates were measured over two consecutive 3-month periods. The introduction of the blood-based test led to a marked increase in overall CRC screening completion: 33 of 74 patients completed screening in Phase 1 (SOC only), compared to 151 of 165 in Phase 2 (SOC plus blood-based test). In Phase 2, the vast majority of patients who completed screening chose the blood-based test (134/151), indicating strong patient preference for this modality over traditional options. The investigators concluded that this study demonstrates that offering a blood-based CRC screening test in primary care settings can substantially improve both screening uptake and completion, particularly in populations with historically low adherence. The study has several important drawbacks. First, the study was conducted in only two primary care clinics in Appalachia, which limits generalizability to other populations and healthcare settings. The sample size was relatively small, and the short duration of each study phase (three months) may not capture longer-term trends in screening behavior or sustainability of increased uptake. Second, the study design did not randomize patients to screening options, introducing potential selection bias and confounding. The observed increase in screening rates may be influenced by unmeasured differences between the two phases or by temporal trends unrelated to the intervention. Third, the study focused on screening uptake and patient preference, but did not assess clinical outcomes such as detection rates of advanced adenomas or colorectal cancer, nor did it report on follow-up colonoscopy completion after positive blood-based tests. This is a critical limitation, as the effectiveness of any screening program depends not only on initial test uptake but also on the sensitivity for advanced neoplasia and adherence to diagnostic follow-up. Fourth, as highlighted by the American Gastroenterological Association, blood-based tests generally have lower sensitivity for advanced adenomas than FIT or stool DNA tests, which may limit their impact on colorectal cancer prevention even if uptake is higher. Finally, the study did not address cost-effectiveness or health system resource implications, which are important considerations for broader implementation.

Blood-Based Protein Biomarkers for Colorectal Cancer Screening

Shah et al. (2014) stated that there is growing interest in the early detection of CRC as current screening modalities lack compliance and specificity. These researchers reviewed the literature to identify biomarkers for the early detection of CRC and polyps. Literature searches were conducted for relevant papers since 2007. Human studies reporting on the early detection of CRC and polyps using biomarkers were included. Methodologic quality was evaluated, and sensitivity, specificity, and the positive predictive value (PPV) were reported. The search strategy identified 3,348 abstracts. A total of 44 papers, examining 67 different tumor markers, were included. Overall sensitivities for CRC detection by fecal DNA markers ranged from 53% to 87%. Combining fecal DNA markers increased the sensitivity of CRC and adenoma detection. Canine scent detection had a sensitivity of detecting CRC of 99% and specificity of 97%. The PPV of iFOBT was 1.26%, compared with 0.31% for the current screening method of gFOBT. A panel of serum protein biomarkers provided a sensitivity and specificity above 85% for all stages of CRC, and a PPV of 0.72%. Combinations of fecal and serum biomarkers produced higher sensitivities, specificities, and PPVs for early detection of CRC and adenomas. The authors concluded that further research is needed to validate these biomarkers in a well-structured population-based study.

Beacon Biomedical, Inc. offers the BeScreened-CRC, an ELISA-based multiplex screening test, that involves testing three blood-based tumor-associated protein biomarkers; an oncoprotein called teratocarcinoma derived growth factor-1 (TDGF-1, Cripto-1); carcinoembryonic antigen (CEA), a well-established biomarker associated with CRC; and an extracellular matrix (ECM) protein involved in early stage tumor stroma changes. These three proteins target immunological activities associated with CRC tumorigenesis; generation, invasion, progression, and migration. This test is designed for those patients over 45 years of age who are at typical average-risk for CRC and who are unwilling or unable to participate in current recommended fecal-based CRC screening tests and colonoscopy procedures. Results are reported as either Negative of Positive for the likely presence of CRC.  Patients who receive negative results are recommended to stay compliant with existing, patient specific screening guidance. Patients who receive positive results are recommended to follow-up with their physician for consult and to schedule a screening colonoscopy. BeScreened-CRC is not a diagnostic test for CRC. It is a screening test that aides in the detection of colorectal cancer and is not intended to replace a colonoscopy. Beacon Biomedical reports 94.6% accuracy at determining the likely presence or absence of CRC. The test kit can be mailed to the patient’s home or healthcare providers office. Beacon Biomedical will contact the patient at home to schedule an at-home blood draw if warranted.

Bhardwaj et al. (2020) state that blood-based protein biomarker signatures might be an alternative or supplement to existing methods for early detection of colorectal cancer (CRC) for population-based screening. The authors worked to obtain a protein biomarker signature for early detection of CRC and its precursor advanced adenoma (AA). In a two-stage design, 270 protein markers were measured by liquid chromatography/multiple reaction monitoring/mass spectrometry in plasma samples of discovery and validation sets. In the discovery set consisting of 100 newly diagnosed CRC cases and 100 age- and sex-matched controls free of neoplasm at screening colonoscopy, the algorithms predicting the presence of early- or late-stage CRC were derived by Lasso regression and .632 + bootstrap. The prediction algorithms were then externally validated in an independent validation set consisting of participants of screening colonoscopy including 56 participants with CRC, 99 with AA and 99 controls without any colorectal neoplasms. Three different signatures for all-, early- and late-stage CRC consisting of five-, three- and eight-protein markers were obtained in the discovery set with areas under the curves (AUCs) after .632 + bootstrap adjustment of 0.85, 0.83 and 0.96, respectively. External validation in the representative screening population yielded AUCs of 0.79 (95% CI, 0.70-0.86), 0.79 (95% CI, 0.66-0.89) and 0.80 (95% CI, 0.70-0.89) for all-, early- and late-stage CRCs, respectively. The three-marker early-stage algorithm yielded an AUC of 0.65 (95% CI, 0.56-0.73) for detection of AA in the validation set. Although not yet competitive with available stool-based tests for CRC early detection, the identified proteins may contribute to the development of powerful blood-based tests for early detection of CRC and its precursors AAs.

Capsule Endoscopy for Colorectal Cancer Screening

Kjolhede and colleagues (2021) noted that colon capsule endoscopy (CCE) is a technology that might contribute to CRC screening programs as a filter test between fecal immunochemical testing and standard colonoscopy. These investigators systematically reviewed the literature for studies examining the diagnostic yield of second-generation CCE compared with standard colonoscopy. They carried out a systematic literature search in PubMed, Embase, and Web of Science. Study characteristics, including the quality of bowel preparation and completeness of CCE transits, were extracted. Per-patient sensitivity and specificity were extracted for polyps (any size, greater than or equal to 10 mm, greater than or equal to 6 mm) and lesion characteristics. Meta-analyses of diagnostic yield were performed. The literature search revealed 1,077 unique papers, and 12 studies were included. Studies involved a total of 2,199 patients, of whom 1,898 were included in analyses. The rate of patients with adequate bowel preparation varied from 40% to 100%. The rates of complete CCE transit varied from 57% to 100%. The meta-analyses demonstrated that mean (95% CI) sensitivity, specificity, and diagnostic odds ratio were: 0.85 (0.73 to 0.92), 0.85 (0.70 to 0.93), and 30.5 (16.2 to 57.2), respectively, for polyps of any size; 0.87 (0.82 to 0.90), 0.95 (0.92 to 0.97), and 136.0 (70.6 to 262.1), respectively, for polyps greater than or equal to 10 mm; and 0.87 (0.83 to 0.90), 0.88 (0.75 to 0.95), and 51.1 (19.8 to 131.8), respectively, for polyps greater than or equal to 6 mm. No serious adverse events (AEs) were reported for CCE. The authors concluded that CCE had high sensitivity and specificity for per-patient polyps compared with standard colonoscopy; however, the relatively high rate of incomplete investigations limited the application of CCE in a CRC screening setting.

Houwen and Dekker (2021) noted that the European Union recommends FIT as the preferred method for population-based screening programs, followed by colonoscopy in FIT-positive individuals. Such FIT-based programs have high participation rates and a positive predictive value (PPV) of approximately 40%, which makes it less attractive to follow a positive FIT with another non-invasive test where no therapy nor pathology-based diagnosis is possible. Thus, CCE might only be a sensible option for those FIT-positive individuals who are unwilling to undergo colonoscopy. In other countries, depending on many factors like the availability of endoscopy services and finances, the preferred screening methods might be different, and primary screening by colonoscopy may be recommended. In these areas, participation rates could possibly be increased by offering CCE as an alternative screening method; however, data from prospective studies on aspects like participation rates, accuracy, patient burden, logistics, and cost-effectiveness are needed first.

In addition, the European Society of Gastrointestinal Endoscopy (ESGE) and the European Society of Gastrointestinal and Abdominal Radiology (ESGAR)’s guideline on “Imaging alternatives to colonoscopy: CT colonography and colon capsule” (Spada et al., 2021) did not suggest CCE as a first-line screening test for CRC (weak recommendation, low-quality evidence).

CD3 Immuno-Staining for Screening of Colon Cancer

Mima et al. (2015) noted that evidence indicates a complex link between the gut microbiome, immunity, and intestinal tumorigenesis. To target the microbiota and immunity for colorectal cancer prevention and therapy, a better understanding of the relationship between microorganisms and immune cells in the tumor microenvironment is needed. Experimental evidence suggested that Fusobacterium nucleatum (F. nucleatum) may promote colonic neoplasia development by down-regulating antitumor T cell-mediated adaptive immunity. These researchers tested the hypothesis that a greater amount of F. nucleatum in colorectal carcinoma tissue is associated with a lower density of T cells in tumor tissue. A cross-sectional analysis was conducted on 598 rectal and colon carcinoma cases in two U.S. nationwide prospective cohort studies with follow-up through 2006: the Nurses' Health Study (participants enrolled in 1976) and the Health Professionals Follow-up Study (participants enrolled in 1986). Tissue collection and processing were performed from 2002 through 2008, and immunity assessment was conducted from 2008 through 2009. From 2013 through 2014, the amount of F. nucleatum in colorectal carcinoma tissue was measured by quantitative polymerase chain reaction assay; these investigators equally dichotomized positive cases (high versus low). Multi-variable ordinal logistic regression analysis was conducted in 2014 to assess associations of the amount of F. nucleatum with densities (quartiles) of T cells in tumor tissue, controlling for clinical and tumor molecular features, including microsatellite instability, CpG island methylator phenotype, long interspersed nucleotide element-1 (LINE-1) methylation, and KRAS, BRAF, and PIK3CA mutation status. They adjusted the two-sided α level to 0.013 for multiple hypothesis testing. Densities of CD3+, CD8+, CD45RO (protein tyrosine phosphatase receptor type C [PTPRC])+, and FOXP3+ T cells in tumor tissue were determined by means of tissue microarray immunohistochemical analysis and computer-assisted image analysis. F. nucleatum was detected in colorectal carcinoma tissue in 76 (13%) of 598 cases. Compared with F. nucleatum-negative cases, F. nucleatum-high cases were inversely associated with the density of CD3+ T cells (for a unit increase in quartile categories of CD3+ T cells as an outcome: multi-variable odds ratio, 0.47 [95% confidence interval (CI): 0.26 to 0.87]; p for trend = 0.006). The amount of F. nucleatum was not significantly associated with the density of CD8+, CD45RO+, or FOXP3+ T cells (p for trend = 0.24, 0.88, and 0.014, respectively). The authors concluded that the amount of tissue F. nucleatum is inversely associated with CD3+ T-cell density in colorectal carcinoma tissue. On validation, their human population data may provide an impetus for further investigations on potential interactive roles of Fusobacterium and host immunity in colon carcinogenesis.

Hagland et al. (2017) tested the feasibility of conducting parallel analyses of circulating T-cells in blood and intra-tumoral T-cells in colorectal cancer. A pre-operative “liquid biopsy” to determine immune status would facilitate clinical decision-making. A total of 18 patients with stage I-III CRC were included. Blood was analyzed for T-cell type (CD3+, CD4+ and CD8+) and count using flow cytometry. Intra-tumoral T-cells were stained using immunohistochemistry and quantified by digital pathology. Tumor location was defined as invasive front (IF) or tumor center (TC). The number of CD3+ and CD4+ T-cells in pre-surgical blood samples correlated with the number of CD3+ T-cells found in the IF (Spearman ϱ = 0.558, p < 0.05 and 0.598, p < 0.01, respectively) and CD3+ in the TC (ϱ = 0.496, p < 0.05, and ϱ = 0.637, p < 0.01, respectively). A strong correlation was found between CD4+ cells in blood and CD8+ T-cells found in the TC and IF (ϱ = 0.602 and ϱ = 0.591, p < 0.01). The authors concluded that there is a correlation between blood CD3+ and CD4+ T-cells and the T-cells found at the TC and IF.

Chromoendoscopy, Confocal Microscopy, and Narrow-Band Imaging Optical Colonoscopy

In vivo analysis can be described as real-time additional imaging that has been suggested for use as an adjunct to endoscopic procedures. The methods include, but may not be limited to, chromoendoscopy, confocal microscopy, fiberoptic analysis, and narrow band imaging. These techniques are utilized during the endoscopic procedures and purportedly improve the analysis of the lesions in the colon. An example of a confocal microscopy device is the Cellvizio system.

Chung et al. (2014) stated that virtual chromoendoscopy (CE) is expected to enhance adenoma yield and reduce variation in performance between colonoscopists. These researchers compared the efficacy of narrow-band imaging (NBI), flexible spectral imaging CE (FICE), and white light (WL) colonoscopy and their impact on less experienced endoscopists. They performed a randomized tandem colonoscopy trial controlling for withdrawal time and bowel preparation. Average-risk adults undergoing screening colonoscopy were enrolled and randomly assigned to first withdrawal with one of the three imaging modalities (NBI (NBI-WL group), FICE (FICE-WL group), and WL (WL-WL group)). Eight colonoscopists were categorized into expert and non-expert subgroups. A total of 1,650 subjects (mean age of 51.4 years, 63.9% men) were included (550 in each group). Compared with WL, neither NBI nor FICE increased the mean number of adenomas detected per patient (0.37 versus 0.35 and 0.36; p = 0.591) or the percentage of patients with adenomas (25.3% versus 24.5% and 23.6%; p = 0.753). For all three modalities, expert subgroups had higher yields of adenomas than non-expert subgroups. Learning curves were observed only for non-expert subgroups with all three modalities. The percentage of missed adenomas did not differ between the three groups (20.8% by WL versus 22.9% by NBI and 26.0% by FICE; p = 0.300) and was not affected by endoscopists' expertise. The authors concluded that neither NBI nor FICE improved adenoma detection or miss rates, with no difference in diagnostic efficacy between the two systems; virtual CE had no additional benefits over WL for non-experts.

Jang et al. (2014) noted that distinguishing deep submucosa (SM) from superficial SM cancer in large sessile and flat colorectal polyps (greater than 2 cm) is crucial in making the most appropriate therapeutic decision. These researchers evaluated the additional role of magnifying NBI and magnifying CE (MCE) in assessing the depth of invasion in large sessile and flat polyps in comparison to morphological evaluation performed by experienced endoscopists. From May 2011 to December 2011, a total of 85 large sessile and flat polyps were analyzed. Endoscopic features of the polyps were independently evaluated by experienced endoscopists. Subsequently, the polyps were observed using magnifying NBI and MCE. A total of 58 intra-mucosal lesions and 27 SM cancers (5 superficial and 22 deep) were identified. The diagnostic accuracy of the experienced endoscopists, NBI, and MCE were 92.9%, 90.6%, and 89.4%, respectively, for deep SM cancer. In combination with NBI or MCE, the diagnostic accuracy of the experienced endoscopists did not change significantly for deep SM cancer, with an accuracy of 95.3% for both NBI and MCE. The authors concluded that conventional colonoscopy can differentiate superficial from deep SM cancers with an accuracy of as high as 92.9% in large sessile and flat polyps.

Colorectal Cancer Screening in Patients with Cystic Fibrosis

Hadjiliadis and colleagues (2018) noted that improved therapy has substantially increased the survival of persons with cystic fibrosis (CF). However, the risk of colorectal cancer (CRC) in adults with CF is 5- to 10-fold greater compared to the general population, and 25 to 30 times greater in CF patients after an organ transplantation. To address this risk, the CF Foundation (CFF) convened a multi-stakeholder task force to develop CRC screening recommendations. The 18-member task force consisted of experts, including pulmonologists, gastroenterologists, a social worker, a nurse coordinator, a surgeon, an epidemiologist, a statistician, a CF adult, and a parent. The committee comprised three work groups: Cancer Risk, Transplant, and Procedure and Preparation. A guidelines specialist at the CFF conducted an evidence synthesis from February to March 2016 based on PubMed literature searches. Task force members conducted additional independent searches. A total of 1,159 articles were retrieved. After initial screening, the committee read 198 articles in full and analyzed 123 articles to develop recommendation statements. An independent decision analysis evaluating the benefits of screening relative to harms and resources required was conducted by the Department of Public Health at Erasmus Medical Center, Netherlands, using the Microsimulation Screening Analysis model from the Cancer Intervention and Surveillance Modeling Network. The task force included recommendation statements in the final guideline only if they reached an 80% acceptance threshold. The task force made 10 CRC screening recommendations that emphasize shared, individualized decision-making and familiarity with CF-specific gastrointestinal challenges. The task force recommended colonoscopy as the preferred screening method, initiation of screening at age 40 years, 5-year re-screening, and 3-year surveillance intervals (unless a shorter interval is indicated by individual findings), and a CF-specific intensive bowel preparation. Organ transplant recipients with CF should initiate CRC screening at age 30 years within 2 years of transplantation because of the additional risk for colon cancer associated with immunosuppression. The authors concluded that these recommendations aim to help CF adults, families, primary care physicians, gastroenterologists, and CF and transplantation centers address the issue of CRC screening. They differed from guidelines developed for the general population with respect to the recommended age of screening initiation, screening method, preparation, and the interval for repeat screening and surveillance.

The National Cancer Institute (NCI) partnered with the CFF to examine the cost-effectiveness of CRC screening in the CF population and to develop screening recommendations from these results. The MISCAN-Colon model was adjusted to account for the increased risk of CRC in CF patients (with and without organ transplant). Colonoscopy every 5 years starting at age 40 was the optimal strategy for CF patients without an organ transplant, and colonoscopy starting at age 30 to 35 was suggested for CF patients with an organ transplant. Methods and recommendations were described in more detail in the study by Gini and associates (2018). These investigators modeled 76 colonoscopy screening strategies that varied the age range and screening interval. The optimal screening strategy was determined based on a willingness-to-pay threshold of $100,000 per life-year gained. Sensitivity and supplementary analyses were performed, including fecal immunochemical testing (FIT) as an alternative test, earlier ages of transplantation, and increased rates of colonoscopy complications, to assess if optimal screening strategies would change. Colonoscopy every 5 years, starting at an age of 40 years, was the optimal colonoscopy strategy for patients with CF who never received an organ transplant; this strategy prevented 79% of deaths from CRC. Among patients with CF who had received an organ transplant, optimal colonoscopy screening should commence at an age of 30 or 35 years, depending on the patient's age at the time of transplantation. Annual FIT screening was predicted to be cost-effective for patients with CF. However, the level of accuracy of the FIT in this population is unclear. The authors concluded that using a Microsimulation Screening Analysis-Colon model, they found screening of patients with CF for CRC to be cost-effective. Because of the higher risk of CRC in these patients, screening should start at an earlier age with a shorter screening interval. The findings of this study (especially those on FIT screening) may be limited by the restricted evidence available for patients with CF.

In a Medscape review on “Screening for colorectal cancer in cystic fibrosis: New risks require new strategies”, Johnson (2019) noted that the recommendations from the CFF were not considered in the CRC screening guidelines produced by the ACS, the U.S. Multi-Society Task Force on Colorectal Cancer, or the ACG.  These new guidelines need to be considered and then reviewed since they are not yet weighted in terms of the strength of the recommendations or the grades of evidence.  That will need to be carried out by the national societies, because these will otherwise not necessarily get paid for.  Most state legislations default to the ACS or the ACG guideline.

Computed Tomographic Colonography

Computed tomographic colonography (CTC), also known as virtual colonoscopy, was developed as a minimally invasive method to examine the colon. This test has been used in screening and to detect abnormalities in the colon and rectum (e.g., colorectal cancer [CRC] and polyps). It involves the use of helical computed tomography (CT) and computer-generated images to produce high-resolution two- and three-dimensional (3D) images of the colon and rectum. Prior to virtual colonoscopy, standard bowel cleansing preparations are needed to evacuate any stool and fluid from the colon. During the procedure, a rectal tube is inserted, and the colon is distended using room air or carbon dioxide, and images are then taken by a helical CT scanner. The results are interpreted by a radiologist. If suspicious lesions are detected, the individual generally must undergo further testing via conventional colonoscopy.

An assessment of CT colonography prepared for the Washington State Health Care Authority (Scherer et al., 2008) found that, in direct comparison to optical colonoscopy, CT colonography every 10 years is substantially more expensive and marginally less effective in preventing cases of cancer (47 versus 52 in a lifetime cohort of 1,000 individuals) and cancer deaths (24 versus 26). The investigators reported that only one CT colonography screening strategy is as effective as optical colonoscopy every 10 years, and that strategy is to perform CT colonography every 5 years with colonoscopy referral for polyps greater than 6 mm. For this strategy, the cost per life-year gained for CT colonography versus optical colonoscopy was $630,700.

The USPSTF (2017) found that evidence for assessing the effectiveness of computed tomography (CT) colonography is limited to studies of its test characteristics. The USPSTF stated that computed tomography colonography can result in unnecessary diagnostic testing or treatment of incidental extracolonic findings that are of no importance or would never have threatened the patient’s health or become apparent without screening (i.e., overdiagnosis and overtreatment). The USPSTF stated that extracolonic findings are common, occurring in about 40% to 70% of screening examinations. Between 5% and 37% of these findings result in diagnostic follow-up, and about 3% require definitive treatment. As with other screening strategies, indirect harms from CT colonography can also occur from follow-up colonoscopy for positive findings.

Drug-Coated Balloon for the Treatment of Colonic Strictures

Shen and Adorno-Garayo (2024) stated that intestinal strictures are common adverse events (AEs) of chronic bowel conditions such as Crohn’s disease (CD), diverticulitis, and ulcerative colitis (UC), or after intestinal surgery. Mechanical endoscopic balloon dilation (EBD) is the standard-of-care (SOC) intervention, whereas multiple, repeat EBD therapy is often needed. A novel drug-coated balloon (DCB) was developed to dilate strictures while concurrently delivering medication to reduce the rate of recurrence of strictures. These researchers presented the findings of a first-in-human, observational, open-label clinical trial in small- and large-bowel strictures. A total of 10 human adult subjects with chronic single, discrete, and benign intestinal strictures were treated and followed for 2 years. Outcomes included the Endoscopic Obstructive Score (EOS), Obstructive Symptom Score (OSS), and AEs. In this first-in-human trial of benign small- and large-bowel strictures, subjects presented with a mean stricture diameter of 10.3 mm, an average EOS of 2.7, and an OSS of 25.2. The technical success rate was 90%, and no subjects had major treatment-related AEs. EOS decreased to 0.2 on average at 6 months. At 2 years, the retreatment-free survival rate was 100%, and the average OSS was 0.6; the procedure was well-tolerated. The authors stated that DCB treatment of benign small- and large-bowel strictures appeared to be safe and showed durable results of decreased symptoms and freedom from recurrence through 2 years. Moreover, these researchers stated that these preliminary findings need to be validated in large-scale clinical trials.

The authors stated that the drawbacks of this trial included the small sample size (n = 10) and limited duration of study follow-up (2 years). Other drawbacks may include the lack of a control group and a lack of diversity in the population cohort. Malignant strictures were also excluded from this study. However, this was the first report of a paclitaxel-coated balloon used to treat intestinal strictures. The POISE Trial was designed as an early-phase study to gain initial experience with the device. Pilot studies such as this are usually carried out with a small number of subjects to examine the early safety and effectiveness of the investigational device before evaluating it in a larger pivotal trial. Follow-up will continue through the 5-year time point for subjects enrolled in this study. These researchers stated that a large randomized controlled trial (RCT) is planned to examine the ProTractX3 DCB against standard EBD and will provide further insight into the risks and benefits associated with this device.

Fecal Occult Blood Test 

Fecal occult blood test (FOBT) is a noninvasive test that detects hidden (occult) blood in the stool. Such blood may come from anywhere along the digestive tract and for that reason additional types of tests may be ordered. Blood in the stool may be the only symptom of early cancer. There are two main types of FOBT tests: guaiac and immunochemical. Fecal immunochemical testing (FIT) differs from guaiac based FOBT in that there are no dietary or drug restrictions prior to this form of testing. Colonoscopy will be needed if the test is positive. Randomized controlled trials (RCTs) have proven that the fecal occult blood test can detect CRC significantly lowers the rate of death from the disease.

The USPSTF (2016) found that multiple randomized clinical trials (RCTs) have shown that screening with the guaiac-based fecal occult blood test (gFOBT) reduces colorectal cancer deaths. Fecal immunochemical tests (FITs), which identify intact human hemoglobin in stool, have improved sensitivity compared with gFOBT for detecting colorectal cancer. Among the FITs that are cleared by the US Food and Drug Administration (FDA) and available for use in the United States, the OC FIT-CHEK family of FITs (Polymedco)--which include the OC-Light and the OC-Auto--have the best test performance characteristics (i.e., highest sensitivity and specificity) (USPSTF, 2016).

Fecal / Stool DNA Testing

Genetic testing of stool samples is also a possible way to screen asymptomatic high-risk individuals for CRC. Colorectal cancer cells are shed into the stool, providing a potential means for the early detection of the disease by detecting specific tumor-associated genetic mutations in stool samples. Fecal/stool DNA testing (sDNA) is performed on stool samples that are submitted to a laboratory after being collected by individuals at home. This test detects CRC based on the presence of specific, cancer associated mutations in DNA extracted from the stool sample. Individuals with a positive sDNA test result must then undergo a definitive test for colon cancer, such as a colonoscopy. sDNA testing is intended as a first line screening test for colon cancer in asymptomatic individuals. An example of an sDNA test is Cologuard, which may detect colorectal neoplasia associated with DNA markers and the presence of occult hemoglobin. 

The USPSTF (2017) stated that multitargeted stool DNA testing (FIT-DNA) is an emerging screening strategy that combines a FIT with testing for altered DNA biomarkers in cells shed into the stool. The USPSTF found that multitargeted stool DNA testing has increased single-test sensitivity for detecting colorectal cancer compared with FIT alone. The harms of stool-based testing primarily result from adverse events associated with follow-up colonoscopy of positive findings. The specificity of FIT-DNA is lower than that of FIT alone, which means it has a higher number of false-positive results and higher likelihood of follow-up colonoscopy and experiencing an associated adverse event per screening test. The USPSTF found no empirical data on the appropriate longitudinal follow-up for an abnormal FIT-DNA test result followed by a negative colonoscopy; there is potential for overly intensive surveillance due to clinician and patient concerns about the implications of the genetic component of the test.

Fecal Volatile Organic Compounds for Colorectal Cancer Screening

Bosch and colleagues (2019) noted that the fecal volatolome, which is composed of fecal volatile organic compounds (VOCs), appeared to hold potential as a non-invasive biomarker for the detection of colorectal cancer (CRC) and its precursor lesions, advanced adenomas (AA). The potential of the fecal volatolome has been the subject of various studies using either chemical analytical or pattern-recognition techniques. These investigators reviewed available literature on the potential of the fecal volatolome as a CRC and AA biomarker. They performed a systematic literature search in PubMed, Embase, the Cochrane Library, Google Scholar, and ResearchGate using the following keywords: colorectal cancer, advanced adenoma, volatile organic compound, metabolome, gas chromatography-mass spectrometry, selected-ion flow-tube mass spectrometry, eNose, and fecal biomarkers. A total of 88 titles or abstracts were identified from the search, of which 11 papers describing the potential of the fecal volatolome for CRC detection were selected. In these studies, different techniques were used for the headspace analyses of fecal VOCs, limiting the possibility to compare outcomes. Increased levels of amino acids and short-chain fatty acids, and decreased levels of bile acids and polyol alcohols in the gas phase of feces were observed repeatedly. All selected papers reported high diagnostic value for the detection of both CRC and AA based on fecal VOCs. The authors concluded that, based on the included studies, fecal VOC analyses appeared promising for future screening of CRC and AA, with potentially improved test performances allowing for earlier detection of AA and CRC; consequently, earlier initiation of treatment could reduce morbidity and mortality rates, along with lower rates of (unnecessary) colonoscopies.

In a systematic review and meta-analysis, van Liere et al. (2023) examined the diagnostic potential of urinary VOCs for CRC and adenomas. By relating VOCs to known pathways, these researchers aimed to gain insight into the pathophysiology of colorectal neoplasia. They carried out a systematic search in PubMed, Embase, and Web of Science. Original studies on urinary VOCs for CRC and adenoma detection with a control group were included. The QUADAS-2 tool was used for quality assessment. A meta-analysis was carried out by adopting a bi-variate model for sensitivity and specificity. Fagan's nomogram estimated the performance of combined FIT-VOC. Neoplasm-associated VOCs were linked to pathways using the KEGG database. A total of 16 studies entailing 837 CRC patients and 1,618 controls were included; 11 performed chemical identification and 7 chemical fingerprinting. In all studies, urinary VOCs discriminated CRC from controls. Pooled sensitivity and specificity for CRC based on chemical fingerprinting were 84% (95% CI: 73% to 91%) and 70% (95% CI: 63% to 77%), respectively. The most distinctive individual VOC was butanal (AUC 0.98). The estimated probability of having CRC following a negative FIT was 0.38%, whereas it was 0.09% following a negative FIT-VOC. Combined FIT-VOC would detect 33% more CRCs. In total, 100 CRC-associated urinary VOCs were identified, particularly hydrocarbons, carboxylic acids, aldehydes/ketones, and amino acids, which were predominantly involved in TCA-cycle or alanine/aspartate/glutamine/glutamate/phenylalanine/tyrosine/tryptophan metabolism, supported by previous research on (colorectal) cancer biology. The potential of urinary VOCs to detect pre-cancerous adenomas or gain insight into their pathophysiology appeared under-studied. The authors concluded that urinary VOCs hold potential for non-invasive CRC screening. These researchers stated that multi-center validation studies are needed, especially focusing on adenoma detection.

Flexible Sigmoidoscopy, Double Contrast Barium Enema, and Colonoscopy

Flexible sigmoidoscopy enables the physician to look at the inside of the large intestine from the rectum through the last part of the colon, called the sigmoid or descending colon. Using this short, flexible fiberoptic tube that is inserted through the anus, the physician can see abnormal growths, bleeding, inflammation, and ulcers in the lower part of the large intestine (colon) and the rectum. If polyps or cancer are found, then a colonoscopy will be necessary to screen for polyps or cancer in the rest of the colon. Although there are no randomized controlled trials (RCTs) proving that sigmoidoscopy reduces the mortality rate from colorectal cancer (CRC), a number of case-control studies have suggested that sigmoidoscopy is effective in reducing CRC mortality. The literature indicates that sigmoidoscopy can detect 70% to 80% of CRC. However, sigmoidoscopy is unable to detect the substantial number of cancers that arise solely in the proximal colon. The literature indicates that some of the additional neoplasms that it misses can be detected by combining sigmoidoscopy with fecal occult blood testing.

The USPSTF (2016) identified several RCTs that show that flexible sigmoidoscopy alone reduces deaths from colorectal cancer. Flexible sigmoidoscopy combined with fecal immunochemical testing (FIT) has been studied in a single trial and was found to reduce the colorectal cancer-specific mortality rate more than flexible sigmoidoscopy alone (citing Holme et al., 2014). The USPSTF noted that modeling studies also consistently estimate that combined testing yields more life-years gained and colorectal cancer deaths averted compared with flexible sigmoidoscopy alone (citing Zauber et al., 2015). Flexible sigmoidoscopy can result in direct harms, such as colonic perforations and bleeding, although the associated event rates are much lower than those observed with colonoscopy. Harms can also occur as a result of follow-up colonoscopy.

Some have advocated whole-bowel screening with colonoscopy or double contrast barium enema (DCBE) because it is able to detect proximal colon lesions. One study found that approximately 30% of cancers detected by colonoscopy would not have been detected by sigmoidoscopy. However, no direct evidence proves that whole-bowel screening, either by colonoscopy or DCBE, reduces mortality, although clinical trials are now underway to investigate this.

Double contrast barium enema (DCBE), also called a lower gastrointestinal (GI) exam, is an x-ray examination of the large intestine (colon and rectum). In a DCBE study, the colon is filled with barium, which helps to see the outline of the colon on an x-ray. The barium is then removed, leaving only a thin layer on the wall of the colon, which is then filled with air. This helps to provide a detailed view of the inner surface of the colon, making it easier to see colon polyps and/or other abnormalities (e.g., inflammation, strictures). If the test is positive, a colonoscopy will be needed for further evaluation. A study comparing the use of colonoscopy to DCBE for patients with previously identified polyps found that colonoscopy detected more polyps than DCBE. Double contrast barium enema found only 20% of adenomatous polyps found by colonoscopy.

Colonoscopy allows the physician to examine the lining of the entire large intestine by using a flexible, fiberoptic instrument (colonoscope) that is inserted through the anus. This test may reveal inflamed tissue, abnormal growths, ulcers, or early signs of cancer in the colon or rectum. Special instruments can be passed through the colonoscope to remove polyps if needed. Although the rate of complications from colonoscopy has been shown to be low, complications from colonoscopy are more common than from other screening procedures. Perforation of the colon and complications from anesthesia have been reported to occur in 0.1% to 0.3% of colonoscopies performed by gastroenterologists, and death occurs in 0.01% of colonoscopies.

The USPSTF (2017) found that completed trials of flexible sigmoidoscopy provide indirect evidence that colonoscopy—a similar endoscopic screening method—reduces colorectal cancer mortality. A prospective cohort study also found an association between patients who self-reported being screened with colonoscopy and a lower colorectal cancer mortality rate. Colonoscopy has both indirect and direct harms. Harms may be caused by bowel preparation prior to the procedure (e.g., dehydration and electrolyte imbalances), the sedation used during the procedure (e.g., cardiovascular events), or the procedure itself (e.g., infection, colonic perforations, or bleeding).

Hsu et al. (2023) investigated the role of double-contrast barium enema (DCBE) as a backup confirmatory examination in colorectal cancer (CRC) screening programs, particularly in countries where it is still recognized when colonoscopy is not feasible or is incomplete. The study aimed to compare the performance of colonoscopy and DCBE regarding the risk of developing incident CRC following negative results from the fecal immunochemical test (FIT) in the Taiwan Colorectal Cancer Screening Program. The cohort included subjects with positive FIT results who underwent confirmatory exams (either colonoscopy or DCBE) between 2004 and 2013, without any neoplastic lesions found. Both groups were followed until the end of 2018, and their data were linked to the Taiwan Cancer Registry to identify new CRC cases. The analysis revealed that 102,761 colonoscopies and 5,885 DCBEs were performed during the study period, resulting in 2,113 CRC cases (2.7 per 1,000 person-years) in the colonoscopy group and 368 CRC cases (7.6 per 1,000 person-years) in the DCBE group by the end of 2018. After adjusting for major confounders, the risk of incident CRC was significantly higher in the DCBE group, with an adjusted hazard ratio of 2.81 (95% CI = 2.51-3.14). The findings suggest that using DCBE as a backup examination in the FIT screening program is associated with nearly three times the risk of incident CRC compared to colonoscopy, indicating that it is no longer a justified alternative for incomplete colonoscopy.

According to the American Cancer Society (ACS, 2024), there are several options for colorectal cancer screening. These include stool-based tests such as the highly sensitive fecal immunochemical test (FIT) and the highly sensitive guaiac-based fecal occult blood test (gFOBT), both recommended annually, as well as the multi-targeted stool DNA test combined with fecal immunochemical testing (mt-sDNA or sDNA-FIT or FIT-DNA), which is suggested every three years. Additionally, visual (structural) examinations of the colon and rectum can be performed, including colonoscopy every ten years, CT colonography (virtual colonoscopy) every five years, and sigmoidoscopy every five years. The ACS does not recommend the use of double-contrast barium enema (DCBE) for CRC screening.

The 2024 American College of Radiology (ACR) Committee on Appropriateness Criteria for colorectal cancer screening indicates that fluoroscopic double-contrast barium enema is "usually not appropriate" for screening individuals at average or high risk for colorectal cancer, as well as for those who have had an incomplete colonoscopy or cannot tolerate the procedure. The use of fluoroscopic barium enema, which employs high-density barium and air insufflation to achieve a double-contrast effect, has declined with the advent of computed tomography colonography (CTC). Research has shown that the fluoroscopic method is less sensitive than CT-based examinations. In the Special Interest Group in Gastrointestinal and Abdominal Radiology (SIGGAR) trial, which randomized 3,838 symptomatic patients to receive either barium enema or CTC in a 2:1 ratio, the detection rate for barium enema was 5.6%, compared to 7.3% for CTC (P = .039). Additionally, a meta-analysis of 11 studies involving double-contrast barium enema (with 5,995 patients and 1,548 polyps) and 30 studies of CTC (with 6,573 patients and 2,348 polyps) found that both the sensitivity and specificity of barium enema were inferior to those of CTC at the 6-mm polyp threshold.

Full-Spectrum Endoscopy (FUSE) Colonoscopy for Screening of Colorectal Cancer

In a retrospective, single-center, feasibility study, Song et al (2016) evaluated the full-spectrum endoscopy (FUSE) colonoscopy system in a Korean population. These researchers examined the effectiveness of the FUSE colonoscopy performed between February 1 and July 20, 2015. A total of 262 subjects (age range of 22 to 80 years) underwent the FUSE colonoscopy for colorectal cancer screening, polyp surveillance, or diagnostic evaluation. The cecal intubation success rate, the polyp detection rate (PDR), the adenoma detection rate (ADR), and the diverticulum detection rate (DDR), were calculated. Also, the success rates of therapeutic interventions were evaluated with biopsy confirmation. All patients completed the study and the success rates of cecal and terminal ileal intubation were 100% with the FUSE colonoscope; these investigators found 313 polyps in 142 patients and 173 adenomas in 95. The overall PDR, ADR and DDR were 54.2%, 36.3%, and 25.2%, respectively, and were higher in males, and increased with age. The endoscopists and nurses involved considered that the full-spectrum colonoscope improved navigation and orientation within the colon. No colonoscopy was aborted because of colonoscope malfunction. The authors concluded that the FUSE colonoscopy yielded a higher PDR, ADR, DDR than did traditional colonoscopy, without therapeutic failure or complications, showing feasible, effective, and safe in this 1st Korean trial.

1. as no other Korean center currently employs the FUSE technology, this was a single-center, retrospective, non-comparative and non-randomized study;
2. these researchers did not use a stop-watch to record time, but they did check the time stamps on the videos taken during each colonoscopy. As these researchers performed many therapeutic interventions, even ESDs, mean total procedure time (18.3 ± 8.6 mins, range of 9 to 48 mins) was thus probably longer than those of other studies. But if they considered only diagnostic interventions, mean total procedure time was shortened to 12.7 ± 1.4 mins (range of 9 to 17 mins),
3. these investigators reported only the presence of a diverticulum, and not the numbers thereof, because many cases had too many diverticula to count, and
4. the authors did not measure the exact polyp size, and thus cannot compare among-study differences in the PDR or ADR by the sizes of polyps or adenomas.

Further, larger comparative studies are needed.

Leong et al. (2017) noted that inflammatory bowel diseases (IBDs) increase the risk of colorectal cancer. Surveillance colonoscopy with chromoendoscopy is recommended, but conventional forward-viewing colonoscopy (FVC) detects dysplasia with low levels of sensitivity. Full-spectrum endoscopy (FUSE) incorporates two additional lateral cameras to the forward camera of the colonoscope, allowing endoscopists to view behind folds and in blind spots, which might increase dysplasia detection. In a prospective, randomized, cross-over, tandem colonoscopy study, these researchers compared FUSE versus FVC in the detection of dysplasia in patients with IBDs. These investigators compared FVC versus FUSE in 52 subjects with IBD undergoing surveillance for neoplasia in Australia (23 with Crohn's colitis, 29 with ulcerative colitis; median age of 45.0 years; 60% men; mean IBD duration of 16.4 years). All subjects met national IBD surveillance inclusion criteria; 27 were assigned randomly to groups that underwent FVC followed by FUSE, and 25 were assigned to groups that underwent FUSE followed by FVC. All procedures were performed from February 2014 through December 2015. Random biopsy specimens were collected, and visible lesions were collected; all were analyzed histologically. The primary endpoint was dysplasia missed by the first colonoscopy detected by the second colonoscopy. Dysplasia was diagnosed by an expert gastrointestinal (GI) pathologist blinded to the colonoscope allocation in consensus with a second expert pathologist. FVC missed 71.4% of dysplastic lesions per lesion, whereas FUSE missed 25.0% per lesion (p = 0.0001); FVC missed 75.0% of dysplastic lesions per subject, and FUSE missed 25.0% per subject (p = 0.046). FUSE identified a mean of 0.37 dysplastic lesions, and FVC identified a mean of 0.13 dysplastic lesions (p = 0.044). The total colonoscopy times were similar (21.2 minutes for FUSE versus 19.1 minutes for FVC; p = 0.32), but withdrawal time was significantly longer for FUSE (15.8 minutes) than for FVC (12.0 minutes) (p = 0.03). Correcting for per-unit withdrawal time, the mean dysplasia miss rate per subject was significantly lower for FUSE (0.19) than for FVC (0.83; p < 0.0001). Targeted tissue acquisition identified significantly more dysplastic lesions than random biopsies (p < 0.0001). The authors concluded that in a prospective cross-over study of IBD patients undergoing surveillance colonoscopy, they found panoramic views obtained by full-spectrum endoscopy increased the number of dysplastic lesions detected compared with conventional forward-viewing colonoscopy. This was a small study examining surveillance for dysplasia in patients with inflammatory bowel diseases.

Ratone et al. (2017) stated that currently, colonoscopy and polypectomy are the gold standard methods for the prevention of incident cases of colorectal cancer. The use of a new colonoscope (Fuse, EndoChoice) with a larger view of up to 330° appears to improve the adenoma detection rate (ADR). In a pilot study, these researchers performed a prospective observational study concerning this scope. The primary endpoint was potentially omitted adenomas (POA), i.e., adenomas seen on the side screens that will not appear on the central display during colonoscopy withdrawal without oriented movements. Secondary endpoints included ADR, Fuse impact on ADR, time to cecal intubation, and withdrawal time. These investigators performed a single-center prospective study in one French center. They enrolled patients over 18 years of age between January 2015 and March 2016. This study included 141 patients (78 men and 60 women; sex ratio 1.3); 3 were excluded because their colonoscopies were incomplete. The mean age was 60.4 years. A total of 130 polyps were resected. In all, 88 out of 130 were adenomas (68%), and 34 out of 88 adenomas (39%) were POA. The mean time to cecum was 10 minutes, and the mean withdrawal time was 12 minutes; ADR was 35% for men and 31% for women. The estimated ADR without POA was 29% for men and 19% for women. The authors concluded that the Fuse system appeared to be safe and efficient; POA represented 39% of all adenomas. The impact of the panoramic view on the ADR was considered substantial. This study had some limitations. First was the possible subjectivity of the primary endpoint. Indeed, though operators described what they considered to be POAs during scope withdrawal, a certain diagnosis was difficult. Nevertheless, a non-POA polyp was also first seen on the side screen and then on the central screen. Of course, the authors did not consider this situation to resemble a POA because POAs required oriented movements to find them on a central screen, but subjectivity remains. Other associated limitations were the lack of randomization or a control group. Moreover, these researchers stated that recently, a high-quality randomized study questioned the utility of Fuse in the detection of adenomas in a population with a positive fecal immunochemical test: no difference was demonstrated in ADR. This new result called into question the superiority of the Fuse, suggested by the feasibility studies and demonstrated by the tandem study of Gralnek et al. This very interesting study encouraged further clinical research into this scope to examine if it represents a minor or major improvement in colorectal cancer screening. Several types of endoscopy centers (expert or not) should be involved in future randomized trials for “real-life” studies.

Bevan and Rutter (2018) stated that “Currently, RCT evidence for colonoscopy screening is scarce. Although not yet corroborated by RCTs, it is likely that colonoscopy is the best screening modality for an individual. From a population perspective, organized programs are superior to opportunistic screening. However, no nation can offer organized population-wide colonoscopy screening. Thus, organized programs using cheaper modalities, such as flexible sigmoidoscopy/fecal immunochemical testing (FS/FIT), can be tailored to budget and capacity.”

Full-Thickness Resection Device (FTRD) for Endoscopic Resection of Appendiceal Polyp

Endoscopic full-thickness resection (EFTR) has emerged as an innovative treatment modality for select subepithelial lesions (SELs). This technique involves the localized excision of a tumor, which often requires dissection through the adjacent muscularis propria to ensure complete removal. EFTR can be performed using either an "exposed" or "nonexposed" technique. The "exposed" technique involves resecting all layers of the gastrointestinal wall, including the mucosa. In contrast, the "nonexposed" approach either preserves an overlying mucosal flap, as seen in the submucosal tunneling endoscopic resection (STER) technique, or employs a "close first, then cut" strategy to minimize the risk of perforation (D'Souza, Yang, and Diehl, 2024).

Valli, Mertens, and Bauerfeind (2018) conducted a study evaluating the safety of endoscopic full-thickness resection (eFTR) using the novel full-thickness resection device (FTRD), the learning curve associated with its implementation, the R0 resection rate, and the clinical outcomes involving a total of 60 patients. The FTRD-mounted endoscope successfully reached the targeted lesion in 97% (58/60) of the procedures, indicating a high technical success rate. Full-thickness resection was achieved in 88% of cases, with an R0 resection confirmed by histological analysis in 79% of patients. The clinical success rate, based on follow-up histology, was even higher at 88%. Adverse events were reported in 7% of cases. One patient developed appendicitis in the residual cecal appendix following eFTR of an adenoma, resulting in the only post-eFTR surgical intervention (1/58, 2%). Minor bleeding at the eFTR site occurred in 2 patients (3%), and one case involved an accidental eFTR without proper prior deployment of the OTSC® (2%). All complications were managed successfully through endoscopic intervention. Importantly, there were no instances of secondary perforation or mortality associated with eFTR. The investigators concluded that, following specialized training, eFTR is a feasible, safe, and promising all-in-one endoscopic resection technique. The study's findings indicated that eFTR facilitates the complete resection of lesions affecting the deeper layers of the gastrointestinal wall with a low incidence of adverse events. However, these preliminary results should be validated in larger, controlled studies to confirm their efficacy and safety.

Bronzwaer et al. (2018) conducted a prospective observational case study to assess the feasibility, technical success, and safety of endoscopic full-thickness resection (eFTR) procedures involving the appendiceal orifice (AO). This study was conducted at a tertiary referral center by two experienced endoscopists. Patients referred for eFTR due to polyps at the AO that could not be resected via endoscopic mucosal resection (EMR)—specifically, those with over 50% circumferential involvement of the AO or deep extension into the AO—were included. The sole exclusion criterion was a lesion diameter exceeding 20 mm. A total of seven patients underwent eFTR for polyps involving the AO. All target lesions were successfully accessed with the FTRD and retracted into the device. Technical success, defined as endoscopic radical en-bloc and full-thickness resection, was achieved in all cases. Histopathological analysis confirmed R0 resection in 85.7% of patients (6 out of 7). One patient, who had a prior appendectomy, developed a small abscess adjacent to the resection site, which was managed conservatively. Another patient experienced secondary appendicitis, necessitating a laparoscopic appendectomy. This preliminary exploratory study indicates that eFTR for appendiceal polyps is feasible and may provide a minimally invasive option for the radical resection of these lesions. However, further research is required to gather safety data and long-term follow-up information to fully evaluate this emerging technique.

Schmidbaur et al. (2021) conducted a retrospective analysis of lesions involving the appendiceal orifice that were treated with endoscopic full-thickness resection (EFTR). Fifty patients underwent EFTR for lesions involving the appendiceal orifice. The primary objective was to assess the incidence of appendicitis following the procedure. During the follow-up period, acute appendicitis was diagnosed in seven patients (14%). Conservative management was effective in four cases, while three patients required an appendectomy. The investigators concluded that EFTR for lesions involving the appendiceal orifice may carry a significant risk of developing appendicitis, potentially necessitating subsequent appendectomy. It is essential to inform patients of this specific risk prior to the resection procedure. The reasons behind the development of appendicitis in some patients, while the majority remain asymptomatic, warrant further investigation.

Ichkhanian et al. (2022) conducted a multicenter international retrospective study aimed at evaluating the outcomes associated with the full-thickness resection device (FTRD) for the excision of appendiceal lesions and identifying factors linked to the development of appendicitis. Consecutive patients who underwent resection of lesions at the appendiceal orifice using the FTRD were included. The primary outcome measure was the rate of R0 resection in neoplastic lesions, defined as having negative lateral and deep margins on post-resection histological evaluation. Secondary outcomes included rates of technical success (en bloc resection), clinical success (technical success without the need for further surgical intervention), post-resection appendicitis, and polyp recurrence. A total of 66 patients (32 women; mean age 64 years) underwent resection of colonic lesions involving the appendiceal orifice, with a mean lesion size of 14.5 mm (standard deviation 6.2). Among these, 40 lesions (61%) were classified as deep, extending into the appendiceal lumen. Technical success was achieved in 59 out of 66 patients (89%), with 56 of these lesions identified as neoplastic on post-resection pathology. Clinical success was attained in 53 out of 66 patients (80%). R0 resection was accomplished in 52 out of 56 neoplastic cases (93%). Of the 58 patients who completed endoscopic full-thickness resection (EFTR) and had no prior history of appendectomy, appendicitis was reported in 10 patients (17%), with six (60%) requiring surgical appendectomy. Follow-up colonoscopy was performed in 41 patients, revealing evidence of recurrence in five patients (12%). The investigators concluded that the FTRD is a promising non-surgical alternative for resecting appendiceal lesions, but appendicitis occurs in 1 out of 6 cases.

Obri et al. (2023) conducted a study to systematically review the literature with a meta-analysis to determine the rate of post-resection appendicitis. This review included studies that utilized a full-thickness resection device (FTRD) for the management of appendiceal polyps. The primary outcome measured was the incidence of appendicitis following FTRD, with a subgroup analysis focusing specifically on studies that reported FTRD procedures performed at the appendiceal orifice. The analysis revealed that appendicitis occurred in 15% of patients (95% Confidence Interval [CI]: [11-21]), with 61% of these cases (95% CI: [44-76]) requiring surgical intervention. In the subgroup of studies (n=123), the pooled rates of technical success, histologic full-thickness resection (FTR), and histologic R0 resection were 92% (95% CI: [85-96]), 98% (95% CI: [93-100]), and 72% (95% CI: [64-84]), respectively. Histopathological evaluation of resected specimens indicated a mean size of 16.8 ± 5.4 mm, with non-neoplastic pathology identified in 9 cases (7%), adenomas in 103 cases (84%), adenomas with high-grade dysplasia (HGD) in 9 cases (7%), and adenocarcinoma in 2 cases (2%). The pooled rate for non-appendicitis-related surgical management, which included technical failures and/or high-risk lesions, was 11% (95% CI: [7-17]). The use of FTRD appears to be an effective approach for managing appendiceal lesions. However, the occurrence of post-resection appendicitis is significant, and the R0 resection rate for appendiceal lesions is only 72%. Therefore, caution is warranted when employing this technique, taking into account the relative risks associated with surgical intervention for each patient.

Justiniano et al. (2024) conducted a study to report on the management of appendiceal orifice mucosal neoplasms utilizing advanced endoscopic techniques. This analysis included patients with appendiceal orifice mucosal neoplasms who underwent advanced endoscopic resections. Techniques employed included endoscopic mucosal resection (EMR), endoscopic submucosal dissection (ESD), hybrid ESD, and combined endoscopic-laparoscopic surgery (CELS). Data regarding patient demographics, lesion characteristics, and procedural outcomes were extracted from a prospectively maintained database. Among 1,005 lesions resected using advanced endoscopic methods, 41 patients (4%) underwent resection of appendiceal orifice mucosal neoplasms. The breakdown of techniques used included hybrid ESD (39%), ESD (34%), EMR (15%), and CELS (12%). The median age of the patients was 65 years, with 54% being male. The median size of the lesions was 20 mm, and dissection was completed piecemeal in 49% of cases. One patient experienced a complication within 30 days post-procedure, presenting with abdominal pain related to polypectomy, which was managed conservatively with a two-day observation period and no further intervention required. Pathological analysis revealed that 49% of the lesions were sessile-serrated, 24% were tubular adenomas, and 15% were tubulovillous adenomas. The median follow-up duration was 8 months (range 0-48 months). One patient with a sessile-serrated lesion experienced recurrence after EMR, which was subsequently re-resected using EMR. Advanced endoscopic techniques for the management of appendiceal orifice mucosal neoplasms demonstrate a low rate of complications and early recurrence. While traditional management often involves surgical resection, these advanced endoscopic approaches present a viable alternative with promising outcomes, allowing for the preservation of the cecum.

Cronin et al. (2025) conducted a study to evaluate the efficacy of endoscopic full-thickness resection (EFTR) for lesions located in the appendiceal orifice (AO). The investigators prospectively analyzed consecutive AO lesions referred for EFTR consideration. Several data points were collected, including technical success rates, histopathological findings from EFTR, adverse events, and follow-up surveillance data obtained through colonoscopy. Surveillance computed tomography (CT) was performed to assess potential mucocele formation resulting from an obstructed remnant appendix. Over a four-year period, 37 AO lesions were referred to a tertiary care center for EFTR evaluation. EFTR was attempted in 35 lesions (95%). The majority of lesions were small, with a median size of 10 mm (interquartile range [IQR] 10-15 mm), and were classified as Paris 0-IIa morphology (n=32, 91%), with serrated histopathology observed in 17 cases (49%). R0 resection was successfully achieved in 30 out of 35 cases (86%). Adverse events included appendicitis in four patients (11%) and delayed bleeding in two patients (6%). At the six-month follow-up colonoscopy (IQR 4-6 months), one case (3%) of a residual lesion was identified, which was successfully managed endoscopically and confirmed on a subsequent surveillance colonoscopy. One case of appendicitis in the remnant appendix occurred seven months post-procedure. Surveillance CT of the abdomen and pelvis (median follow-up of 15 months, IQR 7-37 months) revealed two cases of fistula formation (12%) among the 17 patients, both of whom had a history of presumed adhesions from prior abdominal surgeries. In summary, EFTR is an effective technique for the curative resection of select small (<15 mm) Paris 0-IIa AO lesions. While appendicitis is a relatively common adverse event, it is often manageable with conservative treatment. The long-term implications of fistula formation following EFTR remain uncertain. Caution is advised when considering EFTR in patients with a history of regional abdominal surgery.

High-Risk Testing

More frequent screening has been recommended for persons with a first-degree relative (parent, sibling, or child) with a history of colorectal cancer (CRC). The increased risk of developing cancer at younger ages may justify beginning screening before the age of 50 in persons with a positive family history, especially when affected relatives developed CRC at younger ages. The American Society of Colon and Rectal Surgeons (2010) recommends that people with a first-degree relative with colon cancer or adenomatous polyps diagnosed at age less than 60 years or two first-degree relatives diagnosed at any age should be advised to have screening colonoscopy starting at age 40 years or 10 years younger than the earliest diagnosis in their family, whichever comes first, and repeated every 5 years. The American Society for Gastrointestinal Endoscopy (2006) has a similar position.

Regular colonoscopic screening is part of the routine diagnosis and management of individuals at high risk of developing CRC, including those with a family history of hereditary syndromes (familial polyposis, hereditary non-polyposis colon cancer [HNPCC]); individuals with long-standing ulcerative colitis or Crohn's disease; or high-risk adenomatous polyps or colon cancer. Referral to specialists is appropriate. It has been recommended that persons with a family history of adenomatous polyposis begin screening at puberty, and persons with a family history of HNPCC begin screening at 20 to 30 years of age.

In a meta-analysis of surveillance colonoscopy in individuals at risk for HNPCC, Johnson et al. (2006) concluded that the best available evidence supports surveillance with complete colonoscopy to the cecum every 3 years in patients with HNPCC (B recommendation). There is no evidence to support or refute more frequent screening. Further research is needed to examine the potential harms and benefits of more frequent screening. However, given the potential for rapid progression from adenoma to carcinoma and missing lesions at colonoscopy, there is consensus that screening more frequently than every 3 years is required.

The American College of Gastroenterology (ACG) (Agrawal et al., 2005) issued recommendations to healthcare providers to begin CRC screening in African Americans at age 45 rather than 50 years. Colonoscopy is the preferred method of screening for CRC, and data support the recommendation that African Americans begin screening at a younger age because of the high incidence of CRC and a greater prevalence of proximal or right-sided polyps and cancerous lesions in this population.

MUTYH-associated polyposis (MAP) is an autosomal recessive hereditary syndrome that predisposes individuals to colorectal cancer (CRC). MAP is caused by biallelic germline mutations in the MUTYH gene, which encodes the A/G-specific adenine DNA glycosylase excision repair protein (also called hMYH). MYH is a DNA repair gene that corrects DNA base pair mismatch errors in the genetic code before replication. Mutation of the MYH gene may result in colon cancer. In this regard, the MYH gene has been found to be significantly involved in colon cancer, both in cases where there is a clear family history of the disease, as well as in cases without any sign of a hereditary cause.

The NCCN practice guidelines on "Genetic/familial high-risk assessment: Colorectal" (v.1.2018) recommend colonoscopy surveillance of asymptomatic individuals with known MYH mutations (MUTYH positive mutation) and colonoscopy screening of siblings of affected patients. Surveillance and screening are recommended beginning at age 25 to 30 years and at every 2 to 3 year intervals if negative. If polyps are found (MUTYH-associated polyposis [MAP]), colonoscopy and polypectomy are recommended every 1 to 2 years. Those with a small adenoma burden are surveilled with colonoscopy and complete polypectomies of all polyps. Those with dense polyposis not manageable by polypectomy are recommended surgery. Per NCCN, there are no specific data available to determine screening recommendations for an individual with a MUTYH heterozygous mutation and a second-degree relative affected with CRC.

The NCCN practice guidelines on "Genetic/familial high-risk assessment: Breast and ovarian" (v.2.2019) recommend that persons with Cowden syndrome should consider colonoscopy starting at age 35 years, unless symptomatic or if a close relative has colon cancer before age 40 years, in which case screening should occur every 5 to 10 years before the earliest known colon cancer in the family. Colonoscopy should be done every 5 years or more frequently if the person is symptomatic or if polyps are found.

Concerning risk factors such as smoking and obesity that may warrant more intensive screening, the 2009 American College of Gastroenterology (ACG) guidelines for colorectal cancer (CRC) screening (Rex et al., 2009) did not advocate for initiating screening at an earlier age for smokers and obese individuals. Instead, the ACG suggested further research to evaluate the potential benefits, risks, and cost-effectiveness of earlier screening in these populations.

The American Cancer Society (ACS) indicates that individuals at increased or high risk for colorectal cancer may need to begin screening before the age of 45, undergo more frequent screenings, and/or receive specific tests. This group includes those with a strong family history of colorectal cancer or certain types of polyps, a personal history of colorectal cancer or specific polyps, a history of inflammatory bowel disease (such as ulcerative colitis or Crohn’s disease), a known family history of hereditary colorectal cancer syndromes like familial adenomatous polyposis (FAP) or Lynch syndrome, and those who have received radiation to the abdomen or pelvic area for previous cancer treatment. While the ACS does not provide specific screening guidelines for these high-risk individuals, other organizations, such as the US Multi-Society Task Force on Colorectal Cancer (USMSTF), do offer guidelines that are best discussed with a healthcare provider. Generally, these guidelines categorize individuals based on their specific risk factors. For example, those with a family history of colon or rectal cancer may need to start screening based on the age of diagnosis of affected relatives, while individuals who have had certain polyps removed may require follow-up colonoscopies within three years. Those with a history of colon or rectal cancer typically begin regular colonoscopies about a year after surgery, and individuals who have undergone radiation treatment may need to start screening at an earlier age, often ten years post-radiation or at age 35, whichever is later. For those with inflammatory bowel disease, colonoscopies are generally recommended to start at least eight years after diagnosis, with follow-ups every one to three years. Lastly, individuals with known or suspected genetic syndromes usually require early and frequent colonoscopies, sometimes starting in their teenage years, with the specifics depending on the syndrome and other factors (ACS, 2024).

Methylated Septin9 (ColoVantage, Epi proColon) Testing

The methylated Septin 9 (Sept9) DNA assay, including tests like Epi proColon and ColoVantage, is a plasma-based test used for the early detection of colorectal cancer. It identifies methylated Septin9 DNA, which is believed to indicate the presence of the disease. This test is specifically designed for individuals who have not undergone standard colorectal cancer screening methods, such as colonoscopy, fecal occult blood tests (FOBT), or fecal immunochemical tests (FIT). It is important to note that this test is not intended to replace established screening methods. ColoVantage, in particular, detects circulating methylated DNA from the SEPT9 gene, which is involved in cytokinesis and cell cycle control.

According to the manufacturer for ColoVantage, case-control studies show that the presence of methylated SEPT9 DNA in plasma is 58% to 69% sensitive for CRC detection at a specificity of 86% to 90% (citing Lofton-Day et al., 2008; Grützmann et al., 2008; de Vos et al., 2009). The test is non-invasive and requires no patient preparation. The manufacturer suggests that a physician may order the test for screen-eligible patients who have previously avoided established CRC screening methods such as colonoscopy, FOBT, and fecal immunochemical tests. A patient whose ColoVantage test result is positive may be at increased risk for CRC, and further evaluation should be considered. The manufacturer notes, however, that the ColoVantage test has yet to be clinically validated as a screening test. There are no evidence-based guidelines from leading medical professional organizations or public health agencies that recommend measurement of methylated Septin 9 in plasma for CRC screening.

The ColoVantage blood test was approved by the New York State Health Department for colon cancer in 2011. In a study evaluating the Septin 9 (SEPT9) assay, the sensitivities were found to be 14% for adenomas (1 to 5 cm), 50% for stage I to III colorectal cancer (CRC), and 88% for stage IV CRC, with a false-positive rate of 27%. These results indicate that the serum Septin 9 assay lacks sufficient sensitivity for detecting cancer or precursors at a treatable stage, potentially resulting in a high number of false-positive results.

Molnar and colleagues (2015) noted that many countries have implemented various CRC screening programs but have not achieved the desired compliance. Colonoscopy—considered the gold standard for CRC screening—has its limitations, as do the other techniques used, such as irrigoscopy, sigmoidoscopy, fecal blood, and hemoglobin tests. The biomarker Septin 9 has been found to be hyper-methylated in nearly 100% of tissue neoplasia specimens and detected in circulating DNA fractions of CRC patients. A commercially available assay for Septin 9 has been developed with moderate sensitivity (approximately 70%) and specificity (approximately 90%), and a second-generation assay, Epi proColon 2.0 (Epigenomics AG), shows increased sensitivity (approximately 92%). The performance of the assay proved to be independent of tumor site and reaches a high sensitivity of 77%, even in early cancer stages (I and II). Furthermore, Septin 9 was recently used in follow-up studies for the detection of early recurrence of CRC. The authors evaluated the opportunities, known limitations, and future perspectives of the recently introduced Epi proColon® 2.0 test, which is based on the detection of aberrantly methylated DNA of the v2 region of the Septin 9 gene in plasma.

Jin and associates (2015) evaluated the performance of the Epi proColon 2.0 test for the detection of CRC and compared it with FIT. A total of 135 patients with CRC, 169 with adenomatous polyps, 81 with hyperplastic polyps, and 91 healthy controls were included. In all patients, peripheral blood samples were taken for SEPT9 testing using the Epi proColon 2.0 test. For 177 patients, both SEPT9 and FIT were performed. The sensitivity and specificity of SEPT9 for CRC were 74.8% (95% CI: 67.0 to 81.6%) and 87.4% (versus non-CRC, 95% CI: 83.5 to 90.6%), respectively. SEPT9 was positive in 66.7% of stage I, 82.6% of stage II, 84.1% of stage III, and 100% of stage IV CRCs. The sensitivity of SEPT9 for advanced adenomas was 27.4% (95% CI: 18.7 to 37.6%). The sensitivity and specificity of FIT for CRC were 58.0% (95% CI: 46.1 to 69.2%) and 82.4% (95% CI: 74.4 to 88.7%), respectively. SEPT9 showed better performance in CRC detection than FIT, but similar performance among advanced adenomas. The authors concluded that with improved performance characteristics in detecting CRC, the second-generation SEPT9 assay could play an important role in CRC screening and early detection.

Orntoft et al. (2015) stated that the Sept9 DNA-methylation assay is among the most well-studied blood-based screening markers. However, earlier reported performances may be misleading: the Sept9 test was recently examined in two screening-based cohorts and yielded performances lower than expected. These investigators hypothesized that co-morbidities and/or demographic characteristics affect the results of the Sept9 test. Using a retrospective nested case-control study design, these researchers studied plasma from 150 cancer and 150 controls selected from a well-characterized cohort of 4,698 subjects referred for diagnostic colonoscopy due to CRC-related symptoms. The cases and controls were matched on age and gender. Moreover, cases were stratified by tumor site and tumor stage. The selected cohort included a wide range of co-morbidities. Plasma Sept9 levels were assessed using a commercially available PCR-based assay (Epi proColon). Clinical sensitivity for CRC stages I-IV was 37%, 91%, 77%, and 89%, and the overall sensitivity was 73% (95% CI: 64 to 80%) and specificity 82% (95% CI: 75 to 88%), respectively. Age greater than 65 was associated with both increased false positive and false negative results (p < 0.05). Arthritis was associated with a higher false negative rate (p = 0.005), whereas arteriosclerosis was associated with a higher false positive rate (p = 0.007). Diabetes was associated with Sept9 positivity with an odds ratio (OR) of 5.2 (95% CI: 1.4 to 19.1). When the performance of Sept9 was adjusted for these parameters in a final multivariate regression model, the OR for a positive Sept9 test to be associated with CRC increased from 8.25 (95% CI: 4.83 to 14.09) to 29.46 (95% CI: 12.58 to 69.02). The authors concluded that the findings of this study indicated that the performance of the Sept9 assay is negatively affected by several factors commonly associated with CRC screening populations: early-stage disease, age greater than 65 years, diabetes, arthritis, and arteriosclerosis. This should be taken into account if the Sept9 assay is used as a single marker for CRC screening, but may also have a wider impact, as it is likely that such factors may affect other blood-based DNA markers as well.

On April 14, 2016, the FDA cleared Epi proColon (Epigenomics AG) as the first blood-based screening test for CRC in average-risk patients who choose not to be screened by colonoscopy or a stool-based FIT.

The USPSTF (2016) stated that the FDA approved a blood test, Epi proColon (Epigenomics), to detect circulating methylated SEPT9 DNA in April 2016. A single test characteristic study met the inclusion criteria for the systematic evidence review supporting this recommendation statement; it found the SEPT9 DNA test to have low sensitivity (48%) for detecting colorectal cancer.

The ACS guidelines (Wolf et al., 2018) do not recommend the SEPT9 DNA test, based upon concerns about poor specificity compared with recommended screening options and the limited base of evidence in asymptomatic, screening populations. In addition, the ACS noted that there has been no microsimulation modeling of the current version of the test to estimate its benefit, a benefit-harm ratio, or a screening interval for regular testing, which also has not been established by the manufacturer. Furthermore, methylated Sept9 is a novel blood test for CRC early detection with no comparable screening tests from which to infer a benefit in terms of critical outcomes (CRC mortality or incidence reduction), as there are for the included screening test options. The ACS guidelines note that the test has not been cleared by the FDA for unrestricted use in general routine screening.

MicroRNAs

MicroRNAs (miRNAs) are short non-coding RNA sequences that play an important role in the regulation of gene expression. They have significant regulatory functions in basic cellular processes (e.g., cell differentiation, proliferation, and apoptosis). Available evidence suggests that miRNAs may function as both tumor suppressors and oncogenes. The main mechanism for changes in the function of miRNAs in cancer cells is due to aberrant gene expression.

Dong and colleagues (2011) noted that recent research has shed light on the biological importance of miRNAs in colorectal cancer (CRC) genesis, progression, and response to treatments. The potential utility of miRNAs in the pre-clinical stage has been explored and investigated. These researchers explored the literature and reviewed the cutting-edge progress in the discovery of non-invasive plasma and fecal miRNAs for CRC early diagnosis, as well as their measurability and predictability. They also discussed the utility of miRNAs as novel prognostic and predictive markers and their association with CRC clinical phenotypes, including recurrence, metastasis, and therapeutic outcomes. These investigators summarized miRNA-related single-nucleotide polymorphisms and their potential influence on sporadic CRC susceptibility and therapeutic response. The authors concluded that the use of miRNAs as biomarkers for CRC is still in its infancy and needs further characterization and evaluation.

Sandhu and Garzon (2011) stated that early studies have established that miRNAs are widely deregulated in cancer and play a critical role in cancer pathogenesis. Recent research efforts are now directed towards translating these basic discoveries into novel tests or treatments that could improve the diagnosis and outcome of cancer patients. These researchers summarized the potential applications of miRNAs for cancer diagnosis, prognosis, and treatment, and discussed current pitfalls and future directions. The authors noted that there are still hurdles to overcome, such as the development of reliable and reproducible miRNA expression assays and improvements in oligonucleotide delivery to specific tissues or cell types.

Ma et al. (2012) carried out a comprehensive systematic review of published studies that compared the miRNA expression profiles between CRC tissue and paired neighboring non-cancerous colorectal tissue to determine candidate miRNA biomarkers for CRC. A miRNA ranking system that takes the number of comparisons in agreement, total study sizes, and direction of differential expression into consideration was devised and used. One of the most up-regulated miRNAs, miRNA-106a, was consistently reported to be differentially expressed in six studies, and the five most down-regulated miRNAs—miR-30a-3p, miR-139, miR-145, miR-125a, and miR-133a—were consistently reported to be differentially expressed in four studies. Moreover, these investigators further validated five miRNAs in a clinical setting using quantitative reverse transcription polymerase chain reaction (qRT-PCR), which demonstrated that miR-106a expression was increased, whereas the expression of miR-30a-3p, miR-145, miR-125a, and miR-133a was decreased in the CRC tissues. The authors concluded that these miRNAs may be candidates for developing a panel of biomarkers with sufficient sensitivity and specificity for the diagnosis of CRC in a clinical setting.

Wang et al. (2012) stated that the recently identified class of miRNAs provides new insights in cancer research. As members of the miRNA family, miR-34a, miR-155, and miR-200c abnormalities have been found in various types of cancer. However, the relationship between these three miRNAs (miR-34a, miR-155, and miR-200c) and CRC is unclear. These researchers applied stem-loop real-time PCR to quantitatively detect miR-34a, miR-155, and miR-200c expression in 109 pair-matched human CRC and the corresponding normal mucosa. MiR-34a (2.2-fold), miR-155 (2.3-fold), and miR-200c (3.1-fold) were all expressed at higher levels in CRC (p = 0.001, 0.005, and 0.001, respectively). In the rectum, miR-34a and miR-200c were significantly up-regulated (p = 0.006 and 0.007), while the overexpression of miR-155 was not statistically significant (p = 0.083). In the colon, the higher expression of the three miRNAs was seen; however, without significant difference (p > 0.05). The investigators also found that miR-34a expression was higher in rectal cancer with more advanced TNM stage (III + IV, p = 0.03). Additionally, miR-200c expression was positively correlated with serum CEA levels in rectal cancer patients (p = 0.04). The authors concluded that these findings suggest that the overexpression of miR-34a, miR-155, and miR-200c may be associated with the development of CRC; meanwhile, miR-34a may be involved in the development and progression of rectal cancer. They stated that more in-depth and larger-scale research is required to prove the correlation.

Peacock et al. (2012) noted that accurate discrimination of miRNA profiles between tumor and normal mucosa in CRC allows for the definition of specific expression patterns of miRNAs, giving good potential as diagnostic and therapeutic targets. MicroRNAs expressed in CRC are also abundantly present and stable in stool and plasma samples; their extraction from these sources is feasible and reproducible. The ease and reliability of determining miRNA profiles in plasma or stool make them potential molecular markers for CRC screening.

Kannan et al. (2013) examined the potential use of circulating miRNAs as biomarkers of colorectal adenomas. These investigators screened for 380 plasma miRNAs using microfluidic array technology (Applied BioSystems) in a screening cohort of 12 healthy controls, 9 patients with colorectal adenomas, and 20 patients with CRC. A panel of the most dysregulated miRNAs (p < 0.05, False Discovery Rate: 5%) was then validated in a blinded cohort of 26 healthy controls, 16 patients with large adenomas, and 45 patients with CRC. A panel of eight plasma miRNAs (miR-532-3p, miR-331, miR-195, miR-17, miR-142-3p, miR-15b, miR-532, and miR-652) distinguished polyps from controls with high accuracy [area under curve (AUC) = 0.868 (95% confidence interval [CI]: 0.76 to 0.98)]. In addition, a panel of three plasma miRNAs (miR-431, miR-15b, and miR-139-3p) distinguished stage IV CRC from controls with an AUC = 0.896 (95% CI: 0.78 to 1.0). Receiver-operating characteristic curves of miRNA panels for all CRC versus controls and polyps versus all CRC showed AUC values of 0.829 (95% CI: 0.73 to 0.93) and 0.856 (95% CI: 0.75 to 0.97), respectively. The authors concluded that plasma miRNAs are reliable, non-invasive, and inexpensive markers for colorectal adenomas. They stated that this miRNA panel warrants study in larger cohorts to confirm and then increase its sensitivity and specificity. Plasma-based assays could provide better screening compliance compared to fecal occult blood or endoscopic screening.

Furthermore, a guidance statement from the American College of Physicians on "Screening for colorectal cancer" (Qaseem et al., 2012) does not list miRNA as one of the tests for CRC.

Multi-Target Stool DNA Tests

ColoCaller Test

Ma et al. (2022) noted that because of poor compliance or low sensitivity, existing diagnostic approaches are unable to provide an efficient diagnosis of patients with colorectal cancer (CRC) and gastric cancer. These researchers developed the ColoCaller Test, which simultaneously detects the methylation status of the SDC2, TFPI2, WIF1, and NDRG4 genes in stool DNA, to optimize the screening of CRC and gastric cancer in high-risk populations. A total of 217 stool samples from patients with gastrointestinal (GI) cancer and from patients with negative endoscopy were prospectively collected, complete with pre-operative and post-operative clinical data from patients. The methylation of these samples was detected using ColoCaller, which was designed by selecting CpGs with a two-step screening strategy and was interpreted using a prediction model built using libSVM to examine its clinical value for CRC and gastric cancer screening. Compared to pathological diagnosis, the sensitivity and specificity of the ColoCaller test in 217 stool DNA samples were 95.56% and 91.86%, respectively, for CRC, and 67.5% and 97.81%, respectively, for gastric cancer. The detection limit was as low as 1% in 8 ng of DNA. The authors developed and established a new test, ColoCaller, which can be used as a screening tool or as an auxiliary diagnostic approach in high-risk populations with CRC and gastric cancer to promote timely diagnosis and treatment.

The authors stated that this is the first report on the use of methylated SDC2, TFPI2, WIF1, and NDRG4 genes for early detection of gastric and colorectal cancer (GCC), which not only retains the advantages of simple and non-invasive characteristics similar to fecal occult blood tests (FOBT), but also offers higher sensitivity and specificity for the screening or auxiliary diagnosis of a high-risk population with GCC. At the same time, due to the convenient sampling (home collection) and low costs ($100 to $300 per test), it can be tested repeatedly in clinical applications, which is conducive to continuous monitoring. In the future, a screening method with stool examination as the primary screening and endoscopy as confirmation will be conducive to the popularization and optimization of GCC screening to further improve the detection rate of early gastric cancer and CRC. In addition to being able to directly detect GCC, the ColoCaller test can further stratify a high-risk population to improve endoscopy compliance and promote timely diagnosis and treatment. However, the sample size used in this study to verify the performance of the ColoCaller test was limited, and further investigation is still needed, especially due to the lack of patients with advanced adenomas (AAs). Furthermore, long-term follow-up data are needed to support these findings. Additionally, the detailed clinicopathological characteristics of patients with GCC were not included in this study, which may underestimate the diagnostic performance.

In a systematic review, Dolatkhah et al. (2022) summarized test data and carried out a meta-analysis with respect to the multi-target stool DNA (Mt-sDNA) test sensitivity and specificity compared to colonoscopy. All manuscripts were screened for eligibility according to inclusion criteria. Participants were a normal population at an average risk of developing CRC. The intervention was stool-based, and DNA panel tests were compared with colonoscopy, with the outcome being the detection of CRC and any pre-cancerous lesions. Inter-study inconsistency (using the I-squared test) was assessed. Meta-analyses of the Mt-sDNA test showed a combined sensitivity of 89%, 51%, and 76% for the detection of CRC, advanced adenomas (AA), and combined CRC and AA, respectively. The overall specificity was 91%, 89%, and 90% for the detection of CRC, AA, and combined CRC and AA, respectively. Mt-sDNA had significantly acceptable diagnostic accuracy for CRC and AA diagnosis, but still has lower sensitivity and specificity than colonoscopy.

Cologuard

Redwood and colleagues (2016) evaluated the accuracy of a multi-target stool DNA test (MT-sDNA) compared with fecal immunochemical testing (FIT) for hemoglobin for the detection of screening-relevant colorectal neoplasia (SRN) in Alaska Native people, who have among the world's highest rates of colorectal cancer (CRC) and limited access to conventional screening approaches. These researchers performed a prospective, cross-sectional study of asymptomatic Alaska Native adults aged 40 to 85 years and older undergoing screening or surveillance colonoscopy between February 6, 2012, and August 7, 2014. Among 868 enrolled participants, 661 completed the study (403 [61%] women). Overall, SRN detection by MT-sDNA (49%) was superior to that by FIT (28%; p < 0.001); in the screening group, SRN detection rates were 50% and 31%, respectively (p = 0.01). Multi-target stool DNA testing detected 62% of adenomas 2 cm or larger versus 29% by FIT (p = 0.05). Sensitivity by MT-sDNA increased with adenoma size (to 80% for lesions greater than or equal to 3 cm; p = 0.01 for trend) and substantially exceeded FIT sensitivity at all adenoma sizes. For sessile serrated polyps larger than 1 cm (n = 9), detection was 67% by MT-sDNA versus 11% by FIT (p = 0.07). For CRC (n = 10), detection was 100% by MT-sDNA versus 80% by FIT (p = 0.48). Specificities were 93% and 96%, respectively (p = 0.03). The authors concluded that the sensitivity of MT-sDNA for cancer and larger polyps was high and significantly greater than that of FIT for polyps of any size, while specificity was slightly higher with FIT. They stated that these findings could translate into high cumulative neoplasm detection rates on serial testing within a screening program; the MT-sDNA represents a potential strategy to expand CRC screening and reduce CRC incidence and mortality, especially where access to endoscopy is limited. These investigators stated that further consideration and evaluation of the optimal test frequency, physician and patient acceptance, cost-effectiveness, and logistic algorithms for use and distribution within the Alaska Tribal Health System are needed.

Imperiale et al. (2014) compared a non-invasive, multi-target stool DNA test with a fecal immunochemical test (FIT) in persons at average risk for CRC. The DNA test includes quantitative molecular assays for KRAS mutations, aberrant NDRG4 and BMP3 methylation, and β-actin, plus a hemoglobin immunoassay. Results were generated using a logistic-regression algorithm, with values of 183 or more considered to be positive. Fecal immunochemical test values of more than 100 ng of hemoglobin per milliliter of buffer were considered to be positive. Tests were processed independently of colonoscopic findings. Of the 9,989 participants who could be evaluated, 65 (0.7%) had CRC and 757 (7.6%) had advanced pre-cancerous lesions (advanced adenomas or sessile serrated polyps measuring greater than or equal to 1 cm in the greatest dimension) on colonoscopy. The sensitivity for detecting CRC was 92.3% with DNA testing and 73.8% with FIT (p = 0.002). The sensitivity for detecting advanced pre-cancerous lesions was 42.4% with DNA testing and 23.8% with FIT (p < 0.001). The rate of detection of polyps with high-grade dysplasia was 69.2% with DNA testing and 46.2% with FIT (p = 0.004); the rates of detection of serrated sessile polyps measuring 1 cm or more were 42.4% and 5.1%, respectively (p < 0.001). Specificities with DNA testing and FIT were 86.6% and 94.9%, respectively, among participants with non-advanced or negative findings (p < 0.001) and 89.8% and 96.4%, respectively, among those with negative results on colonoscopy (p < 0.001). The numbers of persons who would need to be screened to detect one cancer were 154 with colonoscopy, 166 with DNA testing, and 208 with FIT. The authors concluded that in asymptomatic persons at average risk for CRC, multi-target stool DNA testing detected significantly more cancers than did FIT but had more false-positive results.

In an editorial that accompanied the aforementioned study, Robertson and Dominitz (2014) stated that “The new multi-target stool DNA test is clearly an improvement over its predecessors, and the results of this study will help to inform the current effort of the U.S. Preventive Services Task Force to reevaluate screening tests. Comparative-effectiveness studies are now needed to clarify the role of stool DNA testing with respect to programmatic screening with other test options. Only through a better understanding of other key factors, such as the screening interval, adherence, cost, and diagnostic evaluation of positive results, can we determine the appropriate place for stool DNA testing on the screening menu.”

Onieva-Garcia and colleagues (2015) evaluated the available evidence on the validity, diagnostic accuracy, and clinical utility of the multi-target DNA test in feces (Cologuard™) for screening for colorectal cancer (CRC). A systematic review was performed by consulting MedLine, EMBASE, and Web of Science to July 2014. Studies on diagnostic tests were selected that evaluated the test in asymptomatic adults who underwent CRC screening. The quality and risk of bias were assessed using the Quality Assessment of Diagnostic Accuracy Studies tool. The level of evidence was defined according to the National Institute for Health and Clinical Excellence. A qualitative synthesis was conducted. A total of 299 literature references were identified, including one synthesis report and five diagnostic test studies; three of the five studies had a case-control design in Sackett phase II and were of moderate quality, and two had a prospective design in Sackett phase III and were of high quality. The sensitivity for detecting CRC was greater than 90%, but only 40% for detecting advanced adenomas. The test provided conclusive diagnostic evidence to rule out CRC (negative likelihood ratio, LR-: 0.02 to 0.09), although it was not useful for ruling out advanced adenoma (LR-: 0.5 to 0.7). The authors concluded that the Cologuard™ test is a valid screening test for ruling out cancerous lesions but is suboptimal for ruling out precancerous lesions. They stated that there is no evidence in terms of mortality, survival, or cost-effectiveness.

Cologuard Plus

Liscu et al. (2024) stated that biomarkers in colorectal cancer (CRC) are of great interest in the current literature due to improvements in techniques such as liquid biopsy and next-generation sequencing (NGS). However, screening methods vary globally, with multi-target stool DNA (mt-sDNA) predominantly used in the U.S. and, more recently, the Cologuard Plus. Biomarkers such as the Galectins family and septins show promise in early detection. Gut microbiome assessments, such as Fusobacterium nucleatum, are under intense exploration. Diagnostic tests, such as circulating DNA analysis via NGS, exhibit effectiveness and are being increasingly adopted. Circulating tumor cells emerge as potential alternatives to traditional methods in terms of diagnosis and prognosis.

Imperiale et al. (2024) evaluated the performance of a next-generation multi-target stool DNA test for colorectal cancer screening. This test includes assessments of DNA molecular markers and hemoglobin levels to enhance specificity and sensitivity compared to previous versions and the fecal immunochemical test (FIT). The study was conducted at 186 sites across the United States, involving 20,176 participants out of 26,758 enrolled. Participants were asymptomatic individuals aged 40 or older scheduled for screening colonoscopy. Exclusions included those with a history of colorectal cancer, advanced precancerous lesions, hereditary cancer syndromes, inflammatory bowel disease, recent positive stool tests, or recent colonoscopy. The primary objective was to determine the sensitivity of the next-generation test for colorectal cancer and its specificity for advanced neoplasia. Secondary objectives included sensitivity for advanced precancerous lesions and specificity for non-neoplastic findings or negative colonoscopy, as well as a comparison with FIT. The next-generation test showed a sensitivity of 93.9% for colorectal cancer and 43.4% for advanced precancerous lesions. Specificity for advanced neoplasia was 90.6%, and for non-neoplastic findings or negative colonoscopy, it was 92.7%. In comparison, FIT had a sensitivity of 67.3% for colorectal cancer and 23.3% for advanced precancerous lesions, with specificities of 94.8% for advanced neoplasia and 95.7% for non-neoplastic findings or negative colonoscopy. Sensitivity for colorectal cancer did not vary significantly by disease stage or location. Sensitivity for advanced precancerous lesions was consistent across age groups and lesion subtypes. Specificity for advanced neoplasia was higher in younger participants, with a decrease observed in older age groups. For colorectal cancer, the positive predictive value was 3.4%, and the negative predictive value was 99.97%. For advanced neoplasia, the positive predictive value was 37.7%, and the negative predictive value was 93.0%. The authors found that the next-generation multi-target stool DNA test demonstrated superior sensitivity for detecting colorectal cancer and advanced precancerous lesions compared to FIT. However, FIT had higher specificity for advanced neoplasia and non-neoplastic findings or negative colonoscopy. Strengths of the study include that it was conducted in a large and diverse participant population, representative of the U.S. screening-eligible population. Another strength was the use of central, blinded adjudication of colorectal cancers, which ensured diagnostic accuracy. Limitations of the study include: 1) a high proportion of participants whose samples could not be evaluated, possibly due to the COVID-19 pandemic; 2) there was no direct comparison with the current version of the multi-target stool DNA test. The authors concluded that the next-generation multi-target stool DNA test showed high sensitivity for colorectal cancer and advanced precancerous lesions, making it a valuable tool for colorectal cancer screening. However, FIT remains superior in specificity for advanced neoplasia.

The authors stated that a drawback of this trial was the relatively high proportion of individuals who provided informed consent and were enrolled but whose samples could not be examined according to the protocol. A contributing factor may have been the conduct of the study during the coronavirus disease 2019 pandemic, which probably affected enrollment and access to colonoscopy. Multiple imputation analyses that accounted for all the subjects showed results consistent with those from the population of participants with evaluable samples. Another drawback was that these researchers did not directly compare the performance of the next-generation multi-target stool DNA test with the current version of the multi-target stool DNA test. Therefore, the results from this study could not be reliably compared with published findings for the multi-target stool DNA test that is currently available for screening purposes, and valid comparisons would require the assessment of both tests in the same persons and specimens concurrently in the context of screening.

In an editorial that accompanied the aforementioned study by Imperiale et al. (2024), Carethers (2024) stated that screening tests for CRC have evolved to include stool-based, endoscopic, image-based, and blood-based methods, with minimal thresholds for sensitivity and specificity for CRC set by the baseline characteristics of FIT. Although multiple tests have been developed over time and vary in cost-effectiveness for CRC screening, the best screening test is the one that gets completed by the patient. Most of the recommended tests, including the two newer tests assessed in the studies now published in the journal, improved on the sensitivity and approached the specificity of FIT, such that these tests appeared to be at least as effective as FIT. Adherence to screening is a key factor, and ease of test use may contribute to increased adherence. Cost-effectiveness and the selection of the testing interval may play roles in adherence, especially in populations that already have lower rates of adherence to CRC screening than the general population. Adherence to screening varies according to age group, including persons in the 45 to 49 years age group who are now eligible for average-risk screening. The editorialist hoped that these newer tests will increase use and adherence and elevate the percentage of the population undergoing screening in order to reduce deaths from CRC.

Multi-Target Stool RNA Test (ColoSense)

ColoSense (Geneoscopy, Inc.) is an FDA-approved, non-invasive multi-target stool RNA (mt-sRNA) test designed for the stabilization and qualitative detection of RNA signals from stool samples, providing a dynamic view of disease activity that is not influenced by age-related methylation patterns. This qualitative in vitro diagnostic test detects RNA markers associated with colorectal neoplasia and occult hemoglobin in human stool. A positive result may indicate the presence of colorectal cancer (CRC), advanced adenomas (AA), or serrated precancerous lesions (SPL), necessitating follow-up with a colonoscopy. ColoSense is intended for screening adults aged 45 and older who are at average risk for developing CRC and is not a substitute for diagnostic or surveillance colonoscopy in high-risk individuals. It is not indicated for those with a personal history of colorectal cancer, adenomas, or related cancers, nor for individuals who have had a positive result from another colorectal cancer screening method within the last 6 months, or specific timeframes for other tests. The ColoSense test is available by prescription and should not be used for individuals under 45 or those at higher risk for colorectal cancer, including those with a history of related cancers or relevant cancer syndromes. Results from the ColoSense test, in conjunction with other clinical information, can assist healthcare providers in assessing the likelihood of colorectal cancer or advanced adenomas.

Yang et al. (2010) attempted to specifically quantify transcripts of fecal cytokeratin 19 (CK19) and ribosomal protein L19 (RPL19) RNA expression in colorectal cancer (CRC) and clarified their correlation with clinicopathological parameters and survival. Solid fecal samples were collected and preserved before any treatment. Levels of fecal CK19 and RPL19 mRNA were measured using quantitative real-time PCR, with an expression level higher than the median value defined as positive. Between April 2001 and June 2007, a total of 92 patients were recruited. The levels of both markers increased in a trend according to stage. Young patients (less than 67 years) were correlated with a higher rate of CK19+ (p = 0.001), as were higher stages, but with borderline significance (p = 0.051). CK19+ and RPL19+ were highly correlated (p = 0.001). Neither CK19+ (p = 0.12) nor RPL19+ (p = 0.14) alone was a prognostic factor for disease-free survival (DFS); however, CK19+/RPL19+ was associated with worse prognosis (p = 0.037), though not as an independent factor in multivariate analysis with stage. The authors concluded that both markers were significantly higher in patients with metastatic disease. The use of both markers would better identify high-risk groups compared to using a single marker, although they have not yet reached independent status. A multi-target strategy assay was suggested for fecal RNA examination.

Iannone et al. (2016) provided an update on current methods for CRC screening based on fecal sample analysis. These investigators conducted a systematic review of the literature in Medline, Embase, and Science Direct electronic databases. Blood in the stools was the first and most commonly used strategy; fecal occult blood tests (FOBT) and fecal immunochemical tests (FIT) are the main methods. Both are economical, easy to perform, with high specificity but low sensitivity. Based on the multi-step process of CRC involving genetic and epigenetic alterations in large bowel cell DNA, single mutations or panels of alterations have been detected. These tests offer a marked improvement in sensitivity compared to fecal blood tests; however, high costs, poor availability, and the correct choice of marker panel represent significant limitations. A specific stool DNA (sDNA) panel, including aberrantly methylated BMP3 and NDRG4 promoter regions, mutant K-ras, and β-actin (a reference gene for human DNA quantity), along with an immunochemical assay for human hemoglobin (Hb), has recently been approved by the FDA. Novel promising biomarkers for CRC screening include microRNAs (miRNAs), which are non-coding RNA molecules that regulate gene expression. Reports on these fecal biomarkers have been case-control studies, each examining single miRNAs or multi-target panels. Conversely, some fecal proteins have been studied as potential CRC screening markers, although they have shown poor results. Additionally, alterations in estrogen receptor-beta (e.g., dramatic reduction in the early stages of CRC) have been demonstrated in tissue samples. The authors concluded that specific investigations are needed to add further non-invasive markers to the panel of CRC screening tools.

Barnell et al. (2021) evaluated a multitarget stool RNA assay combined with fecal immunochemical testing (RNA-FIT) for noninvasive detection of colorectal cancer and precancerous lesions, with the objective of improving sensitivity for advanced neoplasia in average-risk screening populations. The investigators conducted a multicenter study using a large prospective cohort of 1,305 average-risk individuals undergoing screening colonoscopy, supplemented by a small retrospective cohort of 22 patients with known colorectal cancer or advanced adenomas. Stool samples were collected prior to colonoscopy and analyzed using a model that integrated eight stool-derived eukaryotic RNA biomarkers, smoking status, and FIT results. Model development used a training set with internal cross-validation, followed by validation in a holdout testing set, with colonoscopy serving as the reference standard for lesion classification. In the holdout testing set, the RNA-FIT assay demonstrated high sensitivity for colorectal cancer at 95 percent and moderate sensitivity for advanced adenomas at 62 percent, with lower sensitivity for other non-advanced adenomas at 25 percent. Specificity was 80 percent for hyperplastic polyps and 85 percent for individuals with no findings on colonoscopy. The assay also showed strong detection of high-risk lesions, including 100 percent sensitivity for cancers detected at early stage and for advanced adenomas with high-grade dysplasia. These results suggest improved performance relative to existing noninvasive screening modalities, particularly for precancerous lesions that are important for cancer prevention. Several limitations were noted. The study included a relatively small number of colorectal cancer cases, requiring supplementation with retrospective samples that may introduce bias. The decentralized, virtually enrolled design introduced variability in colonoscopy quality and reporting across sites. Specificity was somewhat lower compared with some existing tests, raising the possibility of false positives. In addition, some apparent false positives may reflect missed lesions at colonoscopy, and further validation in larger, strictly prospective cohorts is needed. 

Barnell et al. (2023) stated that non-invasive tests for CRC screening must include sensitive detection of CRC and pre-cancerous lesions. These tests must be validated for the intended-use population, which includes average-risk individuals aged 45 years or older. In a phase III clinical trial, these researchers compared the sensitivity and specificity of a non-invasive, multi-target stool RNA (mt-sRNA) test (ColoSense) with results from colonoscopy. This study (the CRC-PREVENT Trial) was a prospective, blinded, cross-sectional study to support a pre-market approval (PMA) application for a class III medical device. A total of 8,920 subjects were identified online using social media platforms and enrolled from June 2021 to June 2022 using a decentralized nurse call center. All subjects completed the mt-sRNA test, which incorporated a commercially available FIT, the concentration of 8 RNA transcripts, and participant-reported smoking status. Stool samples were collected before subjects completed a colonoscopy at their local endoscopy center. The mt-sRNA test results (positive or negative) were compared with index lesions observed on colonoscopy. Over the course of 12 months, individuals aged 45 years and older were enrolled in the clinical trial using the decentralized recruitment strategy. Subjects were enrolled from 49 U.S. states and obtained colonoscopies at more than 3,800 different endoscopy centers. The primary outcomes included the sensitivity of the mt-sRNA test for detecting CRC and advanced adenomas, as well as the specificity for no lesions on colonoscopy. The mean (range) age of subjects was 55 (45 to 90) years, with 4% self-identified as Asian, 11% as Black, and 7% as Hispanic. Of the 8,920 eligible subjects, 36 (0.40%) had CRC, and 606 (6.8%) had advanced adenomas. The mt-sRNA test sensitivity for detecting CRC was 94%, sensitivity for detecting advanced adenomas was 46%, and specificity for no lesions on colonoscopy was 88%. The mt-sRNA test showed significant improvement in sensitivity for CRC (94% versus 78%; McNemar p = 0.01) and advanced adenomas (46% versus 29%; McNemar p < 0.001) compared with the results of the FIT. The authors concluded that in individuals aged 45 years and older, the mt-sRNA test demonstrated high sensitivity for colorectal neoplasia (CRC and advanced adenoma) with significant improvement in sensitivity relative to the FIT. Specificity for no lesions on colonoscopy was comparable to existing molecular diagnostic tests.

The authors noted several drawbacks to this study. First, center-to-center variations in colonoscopy quality metrics (e.g., adenoma detection rate, withdrawal time), attributable to a physician’s experience, technique, and training, might have increased the false-positive and false-negative rates of the mt-sRNA test. Second, there were differences in participant treatment (e.g., colonoscopy scheduling and bowel preparation) as well as reporting practices in colonoscopy and pathology reports (e.g., nomenclature for sessile serrated lesions, lesion sizing). These factors could have contributed to the variability of results. Third, the decentralized approach likely contributed to the high dropout rate.

Barnell et al. (2024) described the analytical validation of ColoSense for noninvasive colorectal cancer screening, with the primary objective of establishing its analytical performance characteristics to support clinical use. The investigators conducted a series of 12 analytical validation experiments within the CRC-PREVENT framework to evaluate assay performance across key parameters, including limit of blank, limit of detection, limit of quantification, linearity, precision, interfering substances, cross-reactivity, carry-over, cross-contamination, and robustness. The assay integrates a fecal immunochemical test with quantification of eight stool-derived RNA transcripts and smoking status, and uses a centralized laboratory workflow involving droplet digital polymerase chain reaction. Validation testing used a mix of contrived samples generated with synthetic RNA, pooled stool specimens, and clinical samples, with replicate testing across multiple instrument runs, operators, and reagent lots to assess reproducibility and operational variability. The results demonstrated strong analytical performance of the mt-sRNA test. The limits of blank, detection, and quantification were all low, with detection thresholds below 1 copy per milliliter for all markers, and the assay showed linearity across a broad dynamic range from 2.5 to 2500 copies per milliliter. Precision testing showed low coefficients of variation, generally below 20 percent, and high concordance across replicates. There was minimal impact from interfering substances commonly encountered in stool samples, negligible cross-reactivity with noncolorectal cancers and inflammatory conditions, and no evidence of carry-over or cross-contamination. Robustness testing across multiple preanalytic and analytic conditions showed consistent results, supporting reliability under real-world conditions. Several limitations were acknowledged. Many analytical experiments relied on synthetic RNA and contrived samples rather than exclusively native clinical specimens, which may not fully replicate biological variability. The evaluation of cross-reactivity included a relatively small number of samples, limiting definitive conclusions about performance in noncolorectal conditions. In addition, analytical validation of the fecal immunochemical test component was limited because it relied partly on prior regulatory data, raising the possibility of performance differences within the combined assay system. Further studies are needed to confirm these findings in broader clinical contexts and ensure consistent performance across all assay components.

In an accompanying commentary, O’Leary discusses the analytical validation study of the multitarget stool RNA test and its implications for colorectal cancer screening, emphasizing its potential role among expanding noninvasive screening options while highlighting important contextual considerations (O’Leary, 2024). The author placed the ColoSense assay within the broader landscape of colorectal cancer screening, noting that while colonoscopy remains the reference standard, noninvasive tests are essential to improve patient adherence due to convenience and safety advantages. The commentary highlighted that the analytical validation study provides a comprehensive framework for evaluating molecular screening assays, including assessment of analytical sensitivity, precision, and robustness in accordance with Clinical and Laboratory Standards Institute guidelines. At the same time, the author noted that certain methodological details of the test, such as full assay design and decision algorithms, are not fully disclosed, which limits external assessment of reproducibility and mechanistic understanding. O'Leary also evaluated the clinical context by comparing performance characteristics of the stool RNA test with other screening modalities, observing that its sensitivity for colorectal cancer and advanced adenomas appears similar to multitarget stool DNA testing and higher than FIT alone, though direct comparisons are limited by differences in study design. The commentary underscored that real-world effectiveness depends not only on test accuracy but also on patient uptake and adherence to follow-up colonoscopy after positive results, which are known challenges in screening programs. The author further highlighted the importance of tailoring screening strategies to patient preferences and risk profiles, given variability in acceptance of invasive versus noninvasive tests. Several limitations are emphasized. The pivotal clinical trial underlying the assay excluded a substantial proportion of enrolled participants and had issues with sample adequacy, raising concerns about generalizability. The assumption in modeling studies that all positive noninvasive tests are followed by colonoscopy may overestimate real-world benefits. The commentary also noted gaps in transparency regarding assay components and algorithms, as well as broader challenges to adoption such as reimbursement, clinical uptake, and potential intellectual property barriers. Overall, the author concluded that while the mt-sRNA test represents a promising addition to colorectal cancer screening options, its ultimate impact will depend on real-world implementation and comparative effectiveness within the broader screening ecosystem.

In a review titled “Cancer screening: Present recommendations, the development of multi-cancer early detection tests, and the prospect of universal cancer screening,” Gales et al. (2024) noted that the mt-sRNA ColoSense test demonstrated improvements in sensitivity (94%) but remains insufficient for advanced adenomas (46%). However, molecular tumor fingerprinting of early cancers using stool samples remains an attractive area in biomarker research. Furthermore, compared to the standard FOBT, early findings suggested that stool testing could be expanded to include the previously unscreened upper gastrointestinal tract as well. Moreover, techniques need to be optimized and rigorously tested in the clinic to be adequately evaluated for a pan-GI screening test. In the researchers’ opinion, the diagnostic yield of these tests depends on accurately predicting the mutations occurring earliest in tumorigenesis, which may influence the transition from pre-malignant lesions to neoplasia.

In a clinical validation study of a scrape‑free stool collection approach for multitarget stool RNA (mt‑sRNA) testing in colorectal cancer (CRC) screening, Barnell et al. (2026) assessed whether fecal immunochemical testing (FIT) performed in the laboratory is comparable to traditional at‑home FIT and how it affects overall test performance. The study’s objective was to evaluate concordance, sensitivity, and specificity between at‑home and in‑laboratory FIT methods and to determine the impact of laboratory-based FIT integration on mt‑sRNA accuracy. Investigators used banked residual stool samples from 1079 participants in the CRC‑PREVENT pivotal trial, all of whom had completed at‑home FIT, provided stool for mt‑sRNA testing, and subsequently underwent colonoscopy as the reference standard. Identical analytical platforms and thresholds were used for both FIT methods, and statistical comparisons included concordance, positive and negative percent agreement, sensitivity, and specificity relative to colonoscopy findings. Results demonstrated high overall concordance (93%) between at‑home and in‑laboratory FIT, with equivalent sensitivity for CRC detection (75% for both methods among 20 CRC cases). For advanced adenomas, sensitivity was modest but slightly higher with the in‑laboratory method (38% vs 33%, statistically borderline). Specificity for negative colonoscopy findings was similarly high for both approaches (94% at home vs 95% in laboratory), and agreement metrics were strong (positive percent agreement 87% for colorectal neoplasia and negative percent agreement 98% among negative cases). Discordant results occurred in a minority of samples and tended to cluster near assay thresholds; in these cases, in‑laboratory FIT aligned more frequently with colonoscopy findings. When incorporated into the full mt‑sRNA test algorithm, the in‑laboratory FIT yielded calibrated performance of 94% sensitivity for CRC, 48% for advanced adenomas, and approximately 90% specificity for absence of lesions, with no statistically significant difference in overall accuracy compared with use of at‑home FIT alone but modest improvement in detection of advanced precancerous lesions. The study concluded that laboratory-based FIT is a reliable alternative to patient-performed sampling and may improve diagnostic consistency and usability by eliminating patient handling and associated errors, potentially enhancing screening adherence. However, several limitations should be considered: the study population was enriched for advanced lesions, which may affect generalizability to average-risk screening populations; colonoscopy, while the reference standard, may not fully account for variability near FIT thresholds; in‑laboratory FIT testing was performed on samples stored frozen for extended periods, potentially introducing bias; and the study was not designed or powered as a formal noninferiority analysis, limiting definitive comparative conclusions.

The National Comprehensive Cancer Network (NCCN) guidelines for "Colorectal cancer screening" (Version 2.2026) include mt-sRNA test as a CRC screening option, with testing interval every 3 years. The NCCN cites the phase 3 CRC-PREVENT trial by Barnell et al. (2023), which reports a sensitivity of 94% for colon cancer and 46% for advanced adenomas, with a specificity of 86%. Barnell et al. acknowledged that this study had several drawbacks. First, center-to-center variations in colonoscopy quality metrics (e.g., adenoma detection rate, withdrawal time), which were attributable to a physician’s experience, technique, and training might have increased the false-positive and false-negative result rate of the mt-sRNA test. Second, there were differences in participant treatment (e.g., colonoscopy scheduling, and bowel preparation) as well as reporting practices in the colonoscopy and pathology reports (e.g., nomenclature for SSLs, lesion sizing). These factors could have contributed to the variability of results. Third, the decentralized approach likely contributed to the high drop-out rate.

Colorectal cancer screening guidelines from the American Cancer Society (Wolf, et al., 2026) have incorporated the mt-sRNA test (Colosense) as an option for colorectal cancer screening. The guidelines note, however " In the absence of direct comparative studies with mt-sDNA, available evidence suggests that mt-sRNA has comparable sensitivity for detecting CRC and AA. However, its specificity for the absence of advanced colorectal neoplasia is lower than that of ng-mt-sDNA [Cologuard Plus] (85.5% vs. 90.6%, respectively). , , , Lower specificity translates to more colonoscopies done in the follow-up of positive results". 

SimpliPro Colon Test

The SimpliPro Colon Test (Applied Proteomics, Inc., San Diego, CA) is a blood test that uses proprietary mass spectrometry platform and test algorithm designed by Applied Proteomics to measure and analyze 11 protein markers in the blood that are associated with CRC and advanced adenomas. This laboratory-based service is designed to enable better compliance for diagnostic colonoscopy in patients presenting with symptoms associated with CRC. It supposedly is the only blood test that assesses risk for advanced adenoma in elevated-risk patients; however, the SimpliPro Colon test has not been validated in an asymptomatic screening population for CRC.

The American Cancer Society (2017) does not mention the SimpliPro Colon Test as an option for screening of CRC.

Currently, there is a lack of evidence reading the clinical benefit of the SimpliPro Colon Test.

Stool-Based Protein Biomarkers

Bosch and colleagues (2017) stated that the FIT for detecting hemoglobin is used widely for non-invasive CRC screening, but its sensitivity leaves room for improvement. In a case-control study, these researchers identified novel protein biomarkers in stool that out-perform or complement hemoglobin in detecting CRC and advanced adenomas. A total of 315 stool samples from one series of 12 patients with CRC and 10 persons without colorectal neoplasia (control samples) and a second series of 81 patients with CRC, 40 with advanced adenomas, and 43 with non-advanced adenomas, as well as 129 persons without colorectal neoplasia (control samples); 72 FIT samples from a third independent series of 14 patients with CRC, 16 with advanced adenomas, and 18 with non-advanced adenomas, as well as 24 persons without colorectal neoplasia (control samples) were included in this analysis. Stool samples were analyzed by mass spectrometry. Classification and regression tree (CART) analysis and logistic regression analyses were performed to identify protein combinations that differentiated CRC or advanced adenoma from control samples. Antibody-based assays for 4 selected proteins were carried out on FIT samples. In total, 834 human proteins were identified, 29 of which were statistically significantly enriched in CRC versus control stool samples in both series. Combinations of 4 proteins reached sensitivities of 80% and 45% for detecting CRC and advanced adenomas, respectively, at 95% specificity, which was higher than that of hemoglobin alone (p < 0.001 and p = 0.003, respectively). Selected proteins could be measured in small sample volumes used in FIT-based screening programs and discriminated between CRC and control samples (p < 0.001). The authors concluded that mass spectrometry of stool samples identified novel candidate protein biomarkers for CRC screening. Several protein combinations out-performed hemoglobin in discriminating CRC or advanced adenoma from control samples. They stated that this proof of concept study that such proteins can be detected with antibody-based assays in small sample volumes indicated the potential of these biomarkers to be applied in population screening. A main limitation of this study was the lack of availability of antibodies prohibited validation of the top protein combinations in FIT samples.

Whole-Blood DNA Methylation Markers for Risk Stratification in Colorectal Cancer Screening

Raut and colleagues (2019) stated that DNA methylation profiles within whole-blood samples have been reported to be associated with colorectal cancer (CRC) occurrence and might enable risk stratification for CRC. These investigators systematically reviewed and summarized studies addressing the association of whole-blood DNA methylation markers and the risk of developing CRC or its precursors. They searched PubMed and ISI Web of Knowledge to identify relevant studies published until November 12, 2018. Two reviewers independently extracted data on study population characteristics, candidate genes, methylation measurement methods, methylation levels of patients in comparison to healthy controls, p-values, and odds ratios (ORs) of the markers. A total of 19 studies reporting 102 methylation markers for risk assessment of colorectal neoplasms met the inclusion criteria. The studies mostly used methylation-specific polymerase chain reaction (MS-PCR) for assessing the methylation status of a defined set of genes. Only two studies applied array-based genome-wide assays to evaluate the methylation levels; five studies incorporated panels consisting of two to ten individual methylation markers to examine their potential for stratifying the risk of developing colorectal neoplasms. However, none of these associations was confirmed in an independent cohort. The authors concluded that whole-blood DNA methylation markers may be useful as biomarkers for risk stratification in CRC screening, but reproducible risk prediction algorithms are yet to be established by large-scale epigenome-wide studies with thorough validation of results in prospective study cohorts, including large screening populations. The possibilities of enhancing predictive power by combining methylation data with polygenic risk scores and environmental risk factors need to be examined. The authors concluded that there is considerable interest in the use of whole-blood DNA methylation biomarkers to examine the likelihood of developing colorectal neoplasms. However, current risk assessment studies are inconclusive as to which methylation markers are promising for CRC risk stratification. This is due to several limitations in methodology outlined in this study. The variation in methodology and incomplete reporting among the studies also limited the analyses of this review. It is, therefore, strongly recommended that future risk assessment studies apply more standardized methods, particularly in quantifying methylation data. Although time-consuming and expensive, diagnostic and risk stratification performance should preferably be evaluated in screening cohorts or large-scale population-based cohort studies rather than case-control studies in which methylation patterns among cases may have been altered through the course of the disease, after diagnosis, or even initial treatment. Integrating epigenetic and genetic markers may represent a promising approach for future CRC risk stratification schemes. Thus, further research should aim for assessment and validation of the combined performance of genetic and epigenetic markers for CRC risk prediction in order to best define the use of such signatures for research and clinical practice.

The authors stated that this study had several drawbacks. First, these researchers presented only a structured synthesis of multiple study results. Due to the heterogeneity across the reviewed studies, they did not perform a meta-analysis combining the results of independent studies. Second, the selection of studies may have affected the conclusions; even after developing the inclusion/exclusion criteria to ensure that all relevant studies were included, some articles could have been missed. Finally, publication bias, with a tendency to publish more promising results, may have led to overestimated associations in this review.

References