Oral and Esophageal Brush Biopsy

Number: 0686

Table Of Contents

Applicable CPT / HCPCS / ICD-10 Codes


Scope of Policy

This Clinical Policy Bulletin addresses oral and esophageal brush biopsy.

  1. Experimental and Investigational

    Aetna considers the following oral and esophageal procedures experimental and investigational because the effectiveness of these approaches has not been established:

    1. Oral brush biopsy (OralCDx Brush Test), with or without melanoma-associated antigens A (MAGE-A) staining or glucose transporter (GLUT)-1 staining for screening, diagnosis or surveillance of cancerous or pre-cancerous oral lesions;
    2. Esophageal brush biopsy (WATS3D, formerly known as EndoCDx) for screening, diagnosis or surveillance of cancerous or pre-cancerous esophageal lesions;
    3. DNA-image cytometry of brush biopsies for early detection of oral malignancy;
    4. RNA-based oral brush biopsy for the detection and prognosis of oral malignancy;
    5. Use of esophageal balloon for circumferential esophageal cytologic sampling.
  2. Related Policies


CPT Codes / HCPCS Codes / ICD-10 Codes

Code Code Description

Information in the [brackets] below has been added for clarification purposes.   Codes requiring a 7th character are represented by "+":

CPT codes not covered for indications listed in the CPB:

RNA based oral brush biopsy, Esophageal balloon for circumferential cytologic sampling - no specific code:

88104 Cytopathology, fluids, washings or brushings, except cervical or vaginal; smears with interpretation
99000 Handling and/or conveyance of specimen for transfer from the physician's office to a laboratory

Other CPT codes related to the CPB:

40808 Biopsy, vestibule of mouth
41108 Biopsy of floor of mouth
42800 Biopsy; oropharynx
42804     nasopharynx, visible lesion, simple
42806     nasopharynx, survey for unknown primary lesion
43191 Esophagoscopy, rigid, transoral; diagnostic, including collection of specimen(s) by brushing or washing when performed (separate procedure)
43200 Esophagoscopy, flexible, transoral; diagnostic, including collection of specimen(s) by brushing or washing, when performed (separate procedure)
88160 Cytopathology smears, any other source; screening and interpretation

HCPCS codes not covered for indications listed in the CPB:

D0486 Laboratory accession of transepithelial cytologic sample, microscopic examination, preparation and transmission of written report
D7288 Brush biopsy - transepithelial sample collection

Other HCPCS codes related to the CPB:

D7287 Exfoliative cytological sample collection

ICD-10 codes not covered for indications listed in the CPB (not all-inclusive):

D00.00 - D00.08 Carcinoma in situ of lip, oral cavity, and pharynx
D10.0 - D11.9 Benign neoplasm of mouth, pharynx and major salivary glands
D37.01 - D37.02
D37.04 - D37.09
Neoplasm of uncertain behavior of lip, oral cavity, and pharynx
K09.1 - K09.9 Cysts of oral region, not elsewhere classified
K12.0 - K13.79 Stomatitis and related lesions and other diseases of lip and oral mucosa
K14.0 - K14.9 Diseases of tongue
Z12.81 Encounter for screening for malignant neoplasm of oral cavity


Oral Brush Biopsy

The most definitive, accurate, and reliable method for diagnosing oral mucosal lesions is the scalpel biopsy.  The oral brush biopsy coupled with computer-assisted analysis (OralCDx, OralScan Laboratories, Inc., Suffern, NY) has been developed as a technique for evaluating unexplained clinically detectable alterations of the surface epithelium of the oral mucosa whether cancer or pre-cancer is suspected (Sciubba et al, 2003).  The goal of the oral brush biopsy is to provide a highly sensitive and specific technique that is less painful and simpler to perform than a scalpel or punch biopsy.

The oral brush biopsy, using a specially designed circular bristled brush, has been designed to access and sample all epithelial layers, including the basal cell layer and the most superficial aspects of the lamina propria (Sciubba et al, 2003).  Thus, the cellular material obtained should include all epithelial layers in a disaggregated form spread over the surface of a glass slide.

The argument for oral brush biopsy raises 2 questions:
  1. whether indications for oral mucosal biopsy should be expanded to include certain “benign-appearing” lesions, either in high-risk patients (e.g., current or former smokers, heavy drinkers), or in all persons regardless of risk, and
  2. what is the most effective and efficient method of biopsy of oral mucosal lesions. 

Only 1 large-scale study has been published about the use of this technique in the oral cavity (Sciubba et al, 1999).  The study reported that in 945 patients with oral mucosal lesions, the OralCDx had 100 % sensitivity and a zero false negative rate.  The analysis, however, must be considered incomplete, as 618 of 945 brush samples, including 517 of the 699 negative brush samples (73.9 %), were not followed with definitive incisional biopsy for diagnostic confirmation.  In addition, the investigators reported that 7 % of oral brush biopsy specimens were non-diagnostic (Sciubba et al, 1999), which is a much higher incidence than commonly seen with scalpel biopsy (Potter et al, 2002).

A smaller study by Svirsky et al (2002) compared oral brush biopsy results with scalpel biopsy and histology to determine the positive-predictive value (PPV) of an abnormal brush biopsy finding.  Of 243 patients with abnormal brush biopsies, 93 proved positive for dysplasia (n = 79) or carcinoma (n = 14) and 150 were negative for either dysplasia or carcinoma.  Therefore, the PPV of an abnormal brush biopsy was 38 % (93/243).  This smaller study suffers from the same major weakness as the OralCDx Multicenter Study cited above (Sciubba et al, 1999), in that it does not adequately define the negative-predictive value (NPV) of the oral brush biopsy, because only a small proportion of normal brush biopsy results were followed by scalpel biopsy.

Christian (2002) reported on the results of oral brush biopsy in 930 dentists and oral hygienists who were screened for oral cancer while attending the American Dental Association annual session.  Eighty-nine subjects (9.7 %) with 93 oral epithelial lesions were identified and evaluated by brush biopsy.  Seven of the 93 oral lesions -- all benign appearing -- were determined to be “atypical” or “positive” on oral brush biopsy.  Of these, three were diagnosed as precancerous by scalpel biopsy and histological evaluation.  The study by Christian (2002) is of much weaker methodology than the OralCDx Multicenter study cited above.  The study reported by Christian (2002) suffers from the same methodological weaknesses as the OralCDx Multicenter Study, as only some of the positive oral brush biopsy results and none of the negative results were followed by scalpel biopsy.  In addition, the study by Christian (2002) was not a multi-center study, and the subjects (dentists and dental hygienists who volunteered for testing) is not representative of the patient group to which this test is directed (patients seen by their dentist for periodic check-ups and routine cleaning); this raises questions about the generalizabilty of the findings of this study.

There are some reports of significant rates of false negatives from brush biopsy.  Potter et al (2003) examined all diagnoses of oral squamous cell carcinoma from a university oral pathology service over a 2-year period to determine if any had previously undergone brush biopsy reported to be "negative for epithelial abnormality".  Those cases identified were further investigated to determine the time lapse between brush biopsy and definitive tissue diagnosis.  Potter et al (2003) found 4 of 115 squamous cell carcinomas that were reported to be negative on brush biopsy, a false negative rate of 3.5 %.  The authors noted that, because not all 115 squamous cell carcinomas were preceded by a brush biopsy, that the false negative rate for the oral brush biopsy technique may actually be greater.

Although the study by Potter et al (2003) is limited by its retrospective design, it is informative in that it helps define the false negative rate of oral brush biopsy and the clinical consequences of falsely negative results.

Potter et al (2003) stated that the false-negative rate for the oral brush biopsy may be unacceptably high for a diagnostic test.  These researchers explained: "It has been argued that a 3.5 % false-negative rate may be acceptable, particularly if one compares this result with a screening modality like mammography, which has a false-negative rate that varies from approximately 6 % to 25 %.  This analogy, however, is flawed.  Mammography is a screening test directed toward at-risk populations without known disease.  The brush biopsy technique, on the other hand, is directed toward clinically obvious pathologic change, and thus a comparison of false-negative rates with mammography or other screening tests is inappropriate".

Potter et al (2003) went on to explain why the falsely negative results are unlikely to have resulted from an inaccuracy of the data reported by the authors.  They concluded that “[i]t seems that the most likely probability may be that the technique may not be of adequate sensitivity to detect all clinically dysplastic or malignant lesions.”   Furthermore, this study highlights the need to adequately evaluate the rate of false negatives with oral brush biopsy and its consequences.

Although it has been argued that the oral brush biopsy may provide earlier diagnosis of oral cancers and pre-malignant lesions, there are no clinical studies demonstrating this.  The oral brush biopsy has been criticized for adding time and cost to the diagnosis of oral lesions without additional benefit to the patient.  Because the brush biopsy detects only cellular atypia, positive oral brush biopsy results must be confirmed with a scalpel biopsy for definitive diagnosis.  This results in the need for two procedures, rather than one, to establish a diagnosis.  The need to perform two procedures may significantly delay diagnosis.  In the study described above, Potter et al (2003) reported an “undeniably unacceptable” average delay in diagnosis of squamous cell carcinoma between brush and scalpel biopsies.  In the 4 false negative oral brush biopsies identified, the average delay in diagnosis between negative oral brush biopsy and positive scalpel biopsy was 117.2 days (range of 5 to 292 days).  The investigators stated that this delay “can be potentially disastrous.”

The oral brush biopsy technique may also delay diagnosis if the results are negative.  If oral brush biopsy results are negative, no diagnosis is rendered, making it difficult to determine appropriate treatment or anticipate whether an additional procedure is necessary (Potter et al, 2003).

There is insufficient evidence to support the use of oral brush biopsy as a general screening technique for oral cancer or pre-malignant lesions.  A Cochrane evidence review found that there is no evidence from prospective clinical trials that screening with brush biopsy reduces mortality (Kujan et al, 2005; Kujan et al, 2006).  The investigators concluded that “no robust evidence exists” to suggest that brush biopsy for screening of oral cancer or potentially pre-malignant lesions is either beneficial or harmful.

Although the oral brush biopsy technique has been promoted as “painless” (OralScan Laboratories, 2001), there are no studies examining the pain elicited by oral brush biopsy or comparing this pain with that elicited by scalpel biopsy preceded by administration of local anesthetic (Potter et al, 2002).  Given that an adequate oral brush biopsy sample should include all epithelial layers, the contention has been questioned that oral brush biopsy is completely “painless” or that it is substantially less painful than scalpel biopsy with local anesthetic.

The oral brush biopsy technique has also been promoted as easier to perform than scalpel biopsy, such that dentists who are unskilled at performing scalpel biopsy may be able to perform oral brush biopsy (Sciubba et al, 2003).  However, Potter et al (2002) stated that “[f]ear of performing a scalpel biopsy, or inadequate training in its performance, should not be construed as an indication to perform other tests that will further delay completion of the definitive diagnostic test.”

The National Cancer Institute (2004) and the U.S. Preventive Services Task Force (2004) have not recommended routine screening for oral cancer.  Although the American Dental Association has issued a contrary recommendation regarding oral cancer screening, the ADA recommendation does not endorse any specific biopsy method (ADA, 2003; Engber, 2002; Potter et al, 2002; Oral cancer campaign: Editors note, 2002).  The OralCDx Oral Brush Biopsy has gained a seal of acceptance by the American Dental Association’s Council on Dental Therapeutics (ADA, 2001); however, the opinions and evaluations of medical professional organizations are considered according to the scientific quality of the evidence and supporting rationale. An American Dental Association Expert Panel on Screening for Oral Cancers (Rethman, et al., 2010) has concluded that, although transepithelial cytology has validity in identifying disaggregated dysplastic cells, the panel suggests surgical biopsy for definitive diagnosis.

Poate and colleagues (2004) reported that the sensitivity of detection of oral epithelial dysplasia or squamous cell carcinoma of the oral brush biopsy system was 71.4 %; while the specificity was 32 %.  The PPV of an abnormal brush biopsy result (positive or atypical) was 44.1 %; while the NPV was 60 % (n = 112).  These investigators concluded that not all potentially malignant disease is detected with this non-invasive investigative procedure.  Scheifele et al (2004) concluded that further trials on OralCDx (computerized analysis of brush biopsies) as a screening tool of oral lesions are still necessary.  van der Waal (2005) stated that the value of cytological examination, whether obtained by exfoliation of cells or by a brush technique, is somewhat questionable.

Furthermore, in a systematic review on the effectiveness of oral cancer screening, Kujan et al (2006) stated that no robust evidence exists that indicates whether other screening methods including toluidine blue, fluorescence imaging, or brush biopsy are either beneficial or harmful.  These authors noted that further high-quality studies are needed to evaluate the effectiveness of these methods in screening oral cancer.

Driemel and colleagues (2008) assessed the performance of oral brush biopsies using standard morphological analysis and hematoxylin and eosin (HE) staining for detecting oral squamous cell carcinomas and their respective precursor lesions.  Brush biopsies were obtained in 169 consecutive patients who underwent routine biopsies and histological examination for clinically suspicious oral lesions.  Air-dried smears were processed by acetone fixation and HE staining.  Cytological assessment used well-established criteria of atypia to classify the specimen as either tumor-negative (no signs of atypia, no malignant cells) or tumor-positive (malignant cells, any sign of atypia or doubtful cells).  Despite a sufficient number of cells, a definite cytological diagnosis could not be established in 6 cases.  According to the criteria specified above, these specimens were classified as tumor-positive.  The cytological analysis identified 49 out of 62 oral malignancies (sensitivity 79 %).  Seven out of 107 benign lesions were classified as false-positive (specificity 93 %).  The positive and negative predictive values were each 88 %.  The authors concluded that oral brush biopsies will identify only about 80 % of oral malignancies when the smears are processed by routine HE stains and are analyzed via standard morphological criteria.  Thus, this technique should not be used for diagnostic proof or to exclude malignant cells in a lesion suspicious for cancer.

In a systematic review on adjunctive techniques for oral cancer examination and lesion diagnosis, Patton et al (2008) evaluated the effectiveness of toluidine blue (TB), ViziLite Plus with TBlue, ViziLite, Microlux DL, Orascoptic DK, VELscope and OralCDx brush biopsy.  These investigators abstracted data relating to study design, sampling and characteristics of the study group, interventions, reported outcomes and diagnostic accuracy of adjunctive aids from 23 articles meeting inclusion and exclusion criteria, including availability of histological outcomes.  The largest evidence base was for TB.  A limited number of studies was available for ViziLite, ViziLite Plus with TBlue and OralCDx.  Studies of VELscope have been conducted primarily to assess the margins of lesions in known oral pre-malignant and malignant lesions.  The authors identified no studies of Microlux DL or Orascoptic DK.  Study designs had various limitations in applicability to the general practice setting, including use of higher-risk populations and expert examiners.  The authors concluded that there is evidence that TB is effective as a diagnostic adjunct for use in high-risk populations and suspicious mucosal lesions.  OralCDx is useful in assessment of dysplastic changes in clinically suspicious lesions; however, there are insufficient data meeting the inclusion criteria to assess usefulness in innocuous mucosal lesions.  Overall, there is insufficient evidence to support or refute the use of visually based examination adjuncts.  Given the lack of evidence on the effectiveness of adjunctive cancer detection techniques in general dental practice settings, clinicians must rely on a thorough oral mucosal examination supported by specialty referral and/or tissue biopsy for oral pre-malignant and malignant lesions diagnosis.

In a cross-sectional study, Bhoopathi (2009) assessed the effectiveness of the oral brush biopsy technique as a diagnostic tool in detecting dysplastic oral lesions.  Pathologic reports (n = 152) from the scalpel biopsies (tissue samples) in patients who previously tested either "positive" (n = 3) or "atypical" (n = 149) for dysplasia by brush biopsy (OralCDx) were evaluated.  Information on the age and sex of the patient, the site of the lesion, the brush biopsy results, and the histopathological diagnosis of the scalpel biopsy was collected.  The positive predictive values (PPVs) for "abnormal," "atypical," and "positive" brush biopsies were determined.  Overall, the PPV of an abnormal brush biopsy was only 7.9 % (95 % confidence interval [CI]: 4.2 % to 13.4 %), and the PPV of an "atypical" brush biopsy was 7.4 % (95 % CI: 3.7 % to 12.8 %).  Of the 3 positive brush biopsies, only 1 was identified as dysplastic.  The proportion of false-positive biopsy results was as high as 92.1 % (95 % CI: 86.6 % to 95.9 %).  The author concluded that the OralCDx technique over-estimated dysplastic lesions and produced a high number of false-positive results. An evidence review by Juber and Huber (2012) noted limitations of this study, including: the “suspiciousness” of the lesions evaluated was not mentioned; the time frame between OralCDx brush test and scalpel biopsy was not defined; and the investigators were only able to calculate the PPV, because surgical biopsy was only used to evaluate lesions that had previously tested positive with the OralCDx test..

In a prospective, randomized, controlled study, Hohlweg-Majert and associates (2009) evaluated the advantage of computer-assisted analysis of the oral brush biopsy compared with synchronous scalpel biopsy in the early detection of oral lesions.  Brush and scalpel biopsies were performed on 75 patients; 6 patients had to be excluded due to inadequate results, and 43 were shown to have dysplastic epithelium, 15 carcinoma, and 11 suspicious lesions.  Thus, the sensitivity for the detection of abnormal cells by means of OralCDx was 52 %, specificity 29 %, and the PPV 63 %.  According to these findings, the use of oral brush biopsy as a standardized, minimally invasive method of screening oral lesions should be re-considered.

Fedele (2009) stated that the World Health Organization has clearly indentified prevention and early detection as major objectives in the control of the oral cancer burden worldwide.  At the present time, screening of oral cancer and its pre-invasive intra-epithelial stages, as well as its early detection, is still largely based on visual examination of the mouth.  There is strong available evidence to suggest that visual inspection of the oral mucosa is effective in reducing mortality from oral cancer in individuals exposed to risk factors.  Simple visual examination, however, is well known to be limited by subjective interpretation and by the potential, albeit rare, occurrence of dysplasia and early oral squamous cell carcinoma (OSCC) within areas of normal-looking oral mucosa.  As a consequence, adjunctive techniques have been used to increase the ability to differentiate between benign abnormalities and dysplastic/malignant changes as well as to identify areas of dysplasia/early OSCC that are invisible to the naked eye.  These include TB, brush biopsy, chemi-luminescence and tissue auto-fluorescence.  The author reviewed the evidence supporting the efficacy of the afore-mentioned techniques in improving the identification of dysplastic/malignant changes of the oral mucosa; and concluded that available studies have shown promising results, but strong evidence to support the use of oral cancer diagnostic aids is still lacking.  The author stated that further research with clear objectives, well-defined population cohorts, and sound methodology is strongly needed.

Trullenque-Eriksson and colleagues (2009) analyzed publications related to examination techniques that might improve the visualization of suspicious lesions of the oral mucosa (ViziLite system and VELscope system) or that might facilitate the cytological identification of suspicious lesions (OralCDx).  A literature search was performed, using the PubMed database and the key words "brush biopsy", "OralCDx", "ViziLite" and "Velscope", limiting the search to papers in English or Spanish published from 2002 to 2008.  According to the results of studies identified, the ViziLite system has a sensitivity of 100 % and specificity ranging from 0 to 14.2 %, the VELscope system has a sensitivity of 98 to 100 % and specificity of 94 to 100 % and the Oral CDx system has a sensitivity of 71.4 to 100 % and specificity of 32 to 100 %.  The authors concluded that clinical examination and histopathological confirmation with biopsy remain the gold standard for the detection of oral cancer.  Moreover, they noted that more randomized controlled studies are needed to confirm the positive cost-benefit relationship and the true usefulness of these "new diagnostic methods" in oral mucosal pathology.

Toyoshima et al (2009) determined the detection of cytokeratin (CK) mRNA in OSCC cells and evaluated the CK relevance for OSCC diagnosis in a brush biopsy test.  A total fo 52 pairs of OSCC cells and normal oral mucosal cells were obtained by brush biopsy from OSCC patients.  Messenger RNA was extracted from cell pellets for real-time quantitative reverse transcriptase polymerase chain reaction (RT-qPCR).  The over-expression levels of CK 17, CK 19 and CK 20 mRNA in OSCC cells were examined by SYBR green real-time RT-qPCR.  Compared to normal mucosal cells, the over-expression of CK 17 mRNA was detectable in 40 OSCC cells (76.9 %), that of CK 19 mRNA in 19 (36.5 %), while that of CK 20 mRNA was not detectable.  Compared with CK 19, the mean value of CK 17 mRNA expression level was significantly higher in all 52 patients (p < 0.02).  Moreover, the value of CK 17 was significantly higher in T1 and T2 OSCC patients (p < 0.03, respectively), in patients without metastases of neck lymph nodes (p < 0.04), in stage I and stage II patients (p < 0.03 and p < 0.05, respectively) and in well-differentiated OSCC patients (p < 0.05).  The authors concluded that brush biopsy properly serves for detection of CK mRNA using real-time RT-qPCR.  This preliminary study demonstrated the CK 17 possibility for application; however, pivotal studies are needed to confirm CK 17 as a diagnostic marker of OSCC in a brush biopsy test.

Seoane Lestón and Diz Dios (2010) noted that conventional oral exploration (visual and palpation examination) constitutes the current gold standard for oral cancer screening, while biopsy and histopathological examination represents the indispensable study for the detection of cases in patients with an identified lesion.  Imaging techniques (DPT, CT, and MRI) are frequently used to supplement the clinical evaluation and staging of the primary tumor and regional lymph nodes.  There are also a number of techniques that may contribute to the diagnosis of oral cancer: toluidine blue test has been used as a diagnostic aid for the detection of oral cancer over decades.  Recently developed light-based detection systems have progressively improved in sensitivity and specificity, but multi-center controlled studies conducted by general dental practitioners must be designed in order to justify their application.  The oral brush biopsy appears to over-estimate dysplastic lesions and produces a high number of false-positive results.

Remmerbach and colleagues (2011) stated that OSCCs often present as advanced tumors requiring aggressive local and regional therapy and result in significant functional impairment.  The objective is to develop pre-symptomatic screening detection of OSCC by a brush biopsy method that is less invasive than the conventional biopsy for histology.  Given the molecular heterogeneity of oral cancer, it is unlikely that even a panel of tumor markers would provide accurate diagnosis.  Thus, approaches such as the matrix-assisted-laser-desorption/ionisation-time-of-flight-mass-spectrometry (MALDI-TOF-MS) allow several biomarkers or peptide profile patterns to be simultaneously assessed.  Brush biopsies from 27 patients with histology-proven OSCCs plus 40 biopsies from 10 healthy controls were collected.  MALDI-TOF-MS profiling was performed and additional statistical analysis of the data was used to classify the disease status according to the biological behaviour of the lesion.  For classification a support vector machine algorithm was trained using spectra of brush biopsy samples to distinguish healthy control patients from patients with histology-proven OSCC.  MALDI-TOF-MS was able to distinguish between healthy patients and OSCC patients with a sensitivity of 100 % and specificity of 93 %.  The authors concluded that MALDI-TOF-MS in combination with sophisticated bioinformatic methods can distinguish OSCC patients from non-cancer controls with excellent sensitivity and specificity.  Moreover, they stated that further improvement and validation of this approach is needed to determine its feasibility in aiding pre-symptomatic detection of head and neck cancer screening in routine daily practice.

In a cross-sectional study, Bhoopathi and Mascarenhas (2011) evaluated oral surgeons' effectiveness in diagnosing oral dysplastic lesions and compared it to OralCDx brush biopsy.  In this study, the oral surgeon's ability to diagnose dysplasia among 152 consecutive cases (tissue samples) that had previously tested either "positive" (n = 3) or "atypical" (n = 149) for dysplasia by OralCDx brush biopsy was determined by calculating sensitivity, specificity, PPV, and negative predictive value using the scalpel biopsy as the gold standard.  The PPV for oral surgeons and atypical brush biopsy was compared stratified by age, gender, and lesion site.  The PPV, negative predictive value, sensitivity, and specificity for oral surgeons were 10.3 %, 100 %, 100 %, and 23.5 %, respectively.  After controlling for age, gender, and lesion site, oral surgeons were 19 % to 58 % more likely to diagnose a dysplastic lesion compared to OralCDx brush biopsy.  The authors concluded that oral surgeons' effectiveness in diagnosing oral dysplastic lesions was slightly better than the OralCDx brush biopsy; hence, it is recommended that patients be referred to an oral surgeon for evaluation.

Mehrotra et al (2011) performed oral brush biopsies and scalpel biopsies in 85 consecutive patients presenting with an oral lesion deemed to be "minimally suspicious" by clinical examination.  Of 79 patients with adequate brush biopsy samples with matching scalpel biopsies, 27 revealed histopathologic evidence of dysplasia or carcinoma, 26 of which were independently identified with the oral brush biopsy, with a sensitivity of 96.3 % (95 % CI: 87 % to 100 %).  Fifty-two oral lesions did not reveal any histopathologic evidence of dysplasia or carcinoma and of these, brush biopsy reported 47 as "negative" and 5 as "atypical".  The authors reported that the specificity of a "positive" brush biopsy result was 100 % (95 % CI: 93 % to 100 %); the specificity for "atypical" brush biopsy result was 90.4 % (95 % CI: 82 % to 97 %).  The authors found that the positive predictive value of an abnormal oral brush biopsy was 84 % and the negative predictive value was 98 %.  An evidence review (Juber and Huber, 2012) noted limitations of the study by Mehrota, including the fact that the study population has a higher tobacco use and higher prevalence of oral cancer compared to the United States; the definition “minimally suspicious” is open to interpretation; and the location of just under half the lesions was the buccal mucosa, which is considered a low risk area.

Balevi (2011) evaluated the performance of the OralCDx, the VELscope, and toluidine blue staining as clinical adjunctive diagnostic procedures in routine screening for oral cancer in dental practice. The author obtained the sensitivity and specificity for each device from a review of the literature. The author calculated the PPV and false positive rate, based on three clinical screening scenario, using Bayes' Theorem. The author found that, under three clinical scenarios (screening the general population, screening only adults (40 years or older) and screening adults that present with intraoral visible lesions), The author found that the VELscope produced the highest PPV's of 1.27%, 2.53% and 8.11%, respectively, indicating a false positive rate of between 91.89% and 98.73%. The author concluded that the VELscope, OralCDx and toluidine blue staining have high false positive rates when they are used to screen routinely for oral cancer. 

Seijas-Naya and colleagues (2012) evaluated the effectiveness of the brush biopsy technique using OralCDx (OralScan Laboratories Inc., Suffern, NY) as a new method for early diagnosis and control of a "potentially malignant disorder" such as oral leukoplakia.  These investigators performed a study in which samples were taken using OralCDx on 24 patients who visited the Master of Oral Medicine, Oral Surgery and Implantology of the University of Santiago de Compostela between February 2009 and May 2010.  These patients presented clinical and histological lesions that were consistent with oral leukoplakia.  These researchers evaluated the relationship between the keratinization degree of the lesions and cell representation; the diagnosis obtained through OralCDx and biopsies; and sensitivity, specificity, PPV and NPV.  The average age of patients was 62.38 years and 50 % of them were men.  The kappa coefficient relating keratinization of lesions and cell representation was 0.33, the OralCDx - biopsy diagnostic rate reached a kappa value of 0.66, recording 72.7 %, sensitivity and 92.3 % specificity, PPV was 88.8 %, while NPV reached 80 %.  The authors concluded that cytology sampling with OralCDx showed high sensitivity and specificity values, which make it a good tool for monitoring oral leukoplakia, but nowadays the most reliable method that allows confirmation of the exact diagnosis of the lesions and their anatomical and pathological characteristics is still conventional biopsy using a surgical scalpel.

Huber (2012) stated that during the past 10 years, several adjunctive aids have been introduced to the marketplace with the promoted goal of improving the dental practitioner's ability to screen for and identify oral premalignant and malignant lesions (OPMLs).  These products include the OralCDx Brush Test, ViziLite Plus with TBlue, Microlux, VELscope Vx, Sapphire Plus, Identafi, and the DOE Oral Exam System.  They are all marketed as aids for the clinician to use in addition to, not in lieu of, the accomplishment of a conventional oral examination (COE).  Studies addressing the effectiveness of these products when used in the general practice setting to screen for OPMLs are limited and conflicting.  The ability to discriminate between truly dangerous OPML against the milieu of benign mucosal lesions remains a concern and further research is needed to ascertain the true value of these products as marketed to the general practitioner.  The attainment of a complete history and the accomplishment of a thorough and disciplined COE remains the foundation upon which the practitioner evaluates the patient for OPMLs.  Findings deemed suspicious or equivocal should be referred to an expert for further assessment or undergo immediate biopsy, while findings deemed innocuous should be re-evaluated within 2 weeks and referred to an expert for further assessment or undergo biopsy if still present.

An evidence review by Juber and Huber (2012) concluded: “The OralCDx brush test may have the ability to detect dysplasia in innocuous looking oral lesions, but recently published reports continue to have contrasting results pertaining to its overall clinical applicability. Surgical biopsy is still considered the gold standard and should be used to achieve the correct detection and diagnosis”.

In a Cochrane review, Brocklehurst et al (2010) evaluated the effectiveness of current screening methods in decreasing oral cancer mortality.  The following electronic databases were searched: the Cochrane Oral Health Group Trials Register (to May 20, 2010), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2010, Issue 2), MEDLINE via OVID (1950 to May 20, 2010), EMBASE via OVID (1980 to May 20, 2010) and CANCERLIT via PubMed (1950 to May 20, 2010).  There were no restrictions regarding language or date of publication.  Randomized controlled trials (RCTs) of screening for oral cancer or potentially malignant disorders using visual examination, toluidine blue, fluorescence imaging or brush biopsy were selected for review.  The original review identified 1,389 citations and this update identified an additional 330 studies, highlighting 1,719 studies for consideration.  Only 1 study met the inclusion criteria and validity assessment, data extraction and statistics evaluation were undertaken by 6 independent review authors.  One 9-year RCT has been included (n = 13 clusters: 191,873 participants).  There was no statistically significant difference in the age-standardized oral cancer mortality rates for the screened group (16.4/100,000 person-years) and the control group (20.7/100,000 person-years).  A 43 % reduction in mortality was reported between the intervention cohort (29.9/100,000 person-years) and the control arm (45.4/100,000) for high-risk individuals who used tobacco or alcohol or both, which was statistically significant.  However, this study had a number of methodological weaknesses and the associated risk of bias was high.  The authors concluded that although there is evidence that a visual examination as part of a population based screening program reduced the mortality rate of oral cancer in high-risk individuals, while producing a stage shift and improvement in survival rates across the population as a whole, the evidence is limited to 1 study and was associated with a high risk of bias.  This was compounded by the fact that the effect of cluster randomization was not accounted for in the analysis.  Furthermore, no robust evidence was identified to support the use of other adjunctive technologies like toluidine blue, brush biopsy or fluorescence imaging within a primary care environment.  The authors concluded that further RCTs are recommended to assess the efficacy, effectiveness and cost-effectiveness of a visual examination as part of a population based screening program.

The HealthPartners Dental Group and Clinics’ (Minneapolis, MN) oral cancer guideline (2012) stated that “The brush "biopsy", an exfoliative cytologic technique was developed as a means of harvesting a transepithelial sample of cells from an oral surface lesion without having to anesthetize and remove an actual tissue sample (i.e., biopsy specimen) with the scalpel.  This, too, is simply a screening tool similar to one that has been used in gynecology for a number of years and is known as a Papanicolaou ("Pap") smear.  Many dysplastic lesions are first identified by histopathologically evident changes in the morphology of cells in the epithelial basal cell layer.  Therefore, in order to be of use, the brush must obtain cells from this layer.  This test can be used as a preliminary tool in helping to confirm a clinician's suspicion regarding an oral lesion.  It must be emphasized that a brush "biopsy" sample analysis does not and cannot provide a definitive diagnosis for oral cancer.  A tissue biopsy must be obtained to confirm the diagnosis”.

In a Cochrane review, Brocklehurst et al (2013) evaluated the effectiveness of current screening methods in decreasing oral cancer mortality.  These investigators searched the following electronic databases: the Cochrane Oral Health Group's Trials Register (to July 22, 2013), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2013, Issue 6), MEDLINE via OVID (1946 to July 22, 2013), EMBASE via OVID (1980 to July 22, 2013) and CANCERLIT via PubMed (1950 to July 22, 2013).  There were no restrictions on language in the search of the electronic databases.  Randomized controlled trials of screening for oral cancer or potentially malignant disorders using visual examination, toluidine blue, fluorescence imaging or brush biopsy were selected for analysis.  Two review authors screened the results of the searches against inclusion criteria, extracted data and assessed risk of bias independently and in duplicate.  They used mean differences (MDs) and 95 % CIs for continuous data and risk ratios (RRs) with 95 % CIs for dichotomous data.  Meta-analyses would have been undertaken using a random-effects model if the number of studies had exceeded a minimum of 3.  Study authors were contacted where possible and where deemed necessary for missing information.  A total of 3,239 citations were identified through the searches.  Only 1 RCT, with 15-year follow-up met the inclusion criteria (n = 13 clusters: 191,873 participants).  There was no statistically significant difference in the oral cancer mortality rates for the screened group (15.4/100,000 person-years) and the control group (17.1/100,000 person-years), with a RR of 0.88 (95 % CI: 0.69 to 1.12).  A 24 % reduction in mortality was reported between the screening group (30/100,000 person-years) and the control group (39.0/100,000) for high-risk individuals who used tobacco or alcohol or both, which was statistically significant (RR 0.76; 95 % CI: 0.60 to 0.97).  No statistically significant differences were found for incidence rates.  A statistically significant reduction in the number of individuals diagnosed with stage III or worse oral cancer was found for those in the screening group (RR 0.81; 95 % CI: 0.70 to 0.93).  No harms were reported.  The study was assessed as at high-risk of bias.  The authors concluded that there is evidence that a visual examination as part of a population-based screening program reduces the mortality rate of oral cancer in high-risk individuals.  In addition, there is a stage shift and improvement in survival rates across the population as a whole.  However, the evidence is limited to 1 study, which has a high-risk of bias and did not account for the effect of cluster randomization in the analysis.  They stated that there was no evidence to support the use of adjunctive technologies like toluidine blue, brush biopsy or fluorescence imaging as a screening tool to reduce oral cancer mortality; further RCTs are recommended to evaluate the efficacy and cost-effectiveness of a visual examination as part of a population-based screening program in low-, middle- and high-income countries.

Omar (2015) examined the validity of using advanced non-invasive technologies in diagnosis of OSCC by identifying and evaluating relevant published reports.  MEDLINE, EMBASE, and CINAHL were searched to identify clinical trials and other information published between 1990 and June 10, 2014; the searches of MEDLINE and EMBASE were updated to November 2014.  Studies of non-invasive methods of diagnosing OSCC, including oral brush biopsy, optical biopsy, saliva-based oral cancer diagnosis, and others were included.  Data were abstracted and evaluated in duplicate for possible relevance on 2 occasions at an interval of 2 months before being included or excluded.  This study identified 163 studies of non-invasive methods for diagnosing OSCC that met the inclusion criteria. These included six studies of oral brush biopsy, 42 of saliva-based oral diagnosis, and 115 of optical biopsy. Sixty nine of these studies were assessed by the modified version of the QUADAS instrument.  Saliva-based oral cancer diagnosis and optical biopsy were found to be promising non-invasive methods for diagnosing OSCC.  The authors concluded that it is clear that screening for and early detection of cancer and pre-cancerous lesions have the potential to reduce the morbidity and mortality of this disease.  Advances in technologies for saliva-based oral diagnosis and optical biopsy are promising pathways for the future development of more effective non-invasive methods for diagnosing OSCC that are easy to perform clinically in primary care settings.

In a Cochrane review, Macey and colleagues (2015) estimated the diagnostic accuracy of index tests for the detection of oral cancer and potentially malignant disorders (PMD) of the lip and oral cavity, in people presenting with clinically evident lesions. They also estimated the relative accuracy of the different index tests.  The electronic databases were searched on April 30, 2013.  These investigators searched Medline (OVID) (1946 to April 2013) and 4 other electronic databases (the Cochrane Diagnostic Test Accuracy Studies Register, the Cochrane Oral Health Group's Trials Register, Embase (OVID) and Medion (Ovid)).  There were no restrictions on language in the searches of the electronic databases.  They conducted citation searches and screened reference lists of included studies for additional references.  These researchers selected studies that reported the diagnostic test accuracy of the following index tests when used as an adjunct to conventional oral examination in detecting PMD or oral squamous cell carcinoma of the lip or oral cavity: blood or saliva analysis (which test for the presence of biomarkers in blood or saliva), light-based detection and oral spectroscopy, oral cytology, and vital staining.  Two review authors independently screened titles and abstracts for relevance.  Eligibility, data extraction and quality assessment were carried out by at least 2 authors, independently and in duplicate.  Studies were assessed for methodological quality using QUADAS-2.  Meta-analysis was used to combine the results of studies for each index test using the bivariate approach to estimate the expected values of sensitivity and specificity.  The authors included 41 studies, recruiting 4,002 participants, in this review.  These studies evaluated the diagnostic accuracy of conventional oral examination with: light-based detection or oral spectroscopy (13 studies), oral cytology (13 studies), and vital staining (14 studies).  Six studies assessed 2 combined index tests.  There were no eligible diagnostic accuracy studies evaluating blood or salivary sample analysis.  The summary estimates for vital staining obtained from the meta-analysis were sensitivity of 0.84 (95 % CI: 0.74 to 0.90) with specificity of 0.70 (0.59 to 0.79), with 14 studies were included in the meta-analysis.  For cytology, sensitivity was 0.91 (0.81 to 0.96) and specificity was 0.91 (0.81 to 0.95) with 12 studies included in the meta-analysis.  For light-based detection, sensitivity was 0.91 (0.77 to 0.97) and specificity was 0.58 (0.22 to 0.87) with 11 studies included in the meta-analysis.  The relative test accuracy was assessed by adding covariates to the bivariate analysis, no difference in model fit was observed.  The authors concluded that the overall quality of the included studies was poor.  None of the adjunctive tests can be recommended as a replacement for the currently used standard of a scalpel biopsy and histological assessment.  They stated that given the relatively high values of the summary estimates of sensitivity and specificity for cytology, this would appear to offer the most potential.  Moreover, they stated that combined adjunctive tests involving cytology warrant further investigation.

Kujan and associates (2018) examined the applicability of liquid-based cytology (LBC) using an innovative oral brush, Orcellex.  A total of 50 healthy volunteers were recruited.  From each subject, 4 samples were collected using "Orcellex" from apparently normal oral mucosal sites.  A plastic spatula was also used to obtain an additional sample.  Data on the tolerability and acceptability of the Orcellex were collected from the subjects, together with assessments of the adequacy of LBC slide preparations for cellularity, preparation quality, and the types of cells observed.  The Orcellex brush was well-accepted by the volunteers, who reported relatively little pain.  Orcellex brush LBC preparations were of good quality in terms of cell morphology and staining, with a clean background.  Only 2 smears (2/200; 1 %) were found to be inadequate due to low cellularity.  All of the plastic spatula LBC preparations were inadequate.  Representative cells from all layers of the different oral epithelia examined were documented.  The authors concluded that oral liquid-based cytology using the Orcellex brush may have considerable potential for early detection of oral cancer and potentially malignant disorders.  Moreover, these investigators stated that further research is needed to compare the yield obtained using the Orcellex brush with other collection tools and devices.

In a systematic review, H Alsarraf and colleagues (2018) analyzed the published evidence for the use of oral brush cytology for the early detection of oral cancer and oral potentially malignant disorders (OPMDs).  Literature was systematically searched through several databases: Medline, Embase, PubMed, SCOPUS, Cochrane Library, and Web of Science.  Additional review was performed through cross-checks on the bibliographies of selected articles.  The inclusion criteria involved studies assessing the utility of oral brush cytology on human tissues and its applications in the diagnosis, screening, or surveillance of oral cancer or OPMDs.  The search strategy resulted in 343 abstracts or full-text articles, of which 36 met the inclusion criteria.  The year of publication ranged from 1994 to 2017, and a total of 4,302 samples from OPMDs, OSSC, and healthy controls have been investigated.  Baby toothbrush, cytobrush, OralCDx , and Orcellex are the brushes that were used to obtain trans-epithelial mucosal samples for conventional and liquid-based cytology evaluation.  The authors concluded that the findings from this study indicated that meaningful evidence-based recommendations for the implementation of a minimally invasive technique to be utilized as an adjunctive tool for screening and early detection of oral cancer and OPMDs are complicated from the reported studies in the literature.  They stated that there is need for well-designed clinical studies to evaluate the accuracy of oral brush cytology utilizing validated cytological assessment criteria for the diagnosis and prediction of OPMDs.

Kujan and colleagues (2019) examined the feasibility of using oral liquid-based brush cytology (OLBC) coupled with immunocytochemistry as a minimally-invasive approach to stratify the cancer risk in patients with oral leukoplakia.  A total of 55 patients diagnosed with either oral leukoplakia (OLK) or OSCC were recruited.  All patients underwent oral brush biopsy followed by surgical biopsy; 275 liquid-based cytology preparations were made.  Pap stained OLBC slides were assessed using the modified 2014 Bethesda Cytology system.  The expression of CDK4, CDK6, Cyclin D1, and Notch 1 was immunocytochemically analyzed and compared against the histopathological diagnosis.  A combined index score of OLBC grading and protein expression was calculated.  A significant association was found between the definitive histopathological diagnosis and the cytological interpretation (p = 0.0005).  The index scores of CDK4, CDK6, and Cyclin D1 were significantly associated with the development of disease from non-dysplastic epithelium to OSCC.  No significant association was observed between the Notch 1 index score and disease stage.  The diagnostic accuracy of OLBC showed the highest values of sensitivity, specificity, PPV, NPV, and accuracy; 84.6 %, 70.4 %, 73.3 %, 82.6 %, and 78.8 %, respectively, compared to the cumulative protein index, CDK4/6 index, and the combined OLBC grading and CDK4/6 index.  The authors concluded that the findings of this study demonstrated the efficacy of the use of OLBC in the detection of OED and OSCC, and showed that the use of CDK4, CDK6, Cyclin D1 and Notch 1 immunocytochemistry failed to improve the diagnostic accuracy of OLBC suggesting they are not useful in the early detection of OSCC.

Velleuer and colleagues (2020) noted that individuals with Fanconi anemia (FA) have a 500-fold to 700-fold elevated risk, much earlier onset, and limited therapeutic options for OSCC compared with the general population.  The early detection of SCC, or preferably its precursors, is mandatory to retain curative therapeutic options.  Due to frequent synchronic and metachronic oral lesions, tissue biopsies, as usually recommended by guidelines, often are not feasible.  In the current study, an alternative strategy for early detection using oral brush biopsy-based cytology was examined regarding its diagnostic accuracy.  Over a 12-year period, the oral cavities of a large cohort of 713 individuals with FA were inspected systematically and brush biopsy-based cytology of 1,233 visible oral lesions was performed.  In cases of inconclusive cytology, analysis of DNA ploidy was performed whenever possible.  The results were correlated to a long-term clinicopathological follow-up reference standard.  A total of 737 lesions were suitable for statistical analysis, including 86 lesions with at least high-grade oral epithelial dysplasia (OED) in 30 patients.  For cytology, the sensitivity and specificity were 97.7 % and 84.5 %, respectively.  Additional analysis of DNA ploidy increased the sensitivity and specificity to 100 % and 92.2 %, respectively.  The authors concluded that careful inspection of the oral cavity of individuals with FA followed by brush biopsy-based cytology appeared to identify visible oral, potentially malignant and malignant lesions that warrant treatment.  Approximately 63 % of SCC and precursor lesions were detected at a non-invasive or early stage.  Negative cytology or a lack of DNA aneuploidy could exclude high-grade oral epithelial dysplasia or SCC with high accuracy and thereby reducing the need for invasive diagnostic biopsies.

The authors stated that the drawbacks of this study were that the oral examinations and cytological investigations were carried out by 1 work group and the screening approach was opportunistic and not population-based; therefore, it was not possible to estimate the NPV for an FA population-based cytological screening for OED or oral SCC.

Kujan et al (2021) examined the effectiveness of using OLBC and cell block immunocytochemistry in the diagnosis of oral leukoplakia as minimally invasive diagnostic adjuncts.  A total of 72 patients diagnosed clinically with either OLK or OSCC were included.  Oral brush samples using Orcellex brushes were obtained from all subjects directly before undergoing surgical biopsy.  Cell blocks were prepared for all samples and examined for cytomorphology and immunocytochemistry of DNA mismatch repair proteins (MSH-6, MSH-2, MLH-1 and PMS-2).  A combined index score of immunocytochemistry expression and cytology grading was compared against the gold standard (histopathological diagnosis).  A significant association was observed between the cytological assessments of OLBC samples and the histopathological diagnosis (p < 0.005).  Furthermore, there was a significant inverse correlation between the grade of oral epithelial dysplasia and the cumulative score of the studied DNA mismatch repair proteins (p < 0.005).  Grading criteria for both OLBC and immunocytochemistry cumulative index scores are proposed based on the analysis of ROC curve coordinates.  The diagnostic accuracy of this approach was outstanding in terms of discrimination between the presence or absence of oral epithelial dysplasia (0.961) and SCC (0.977), respectively.  The authors concluded that OLBC cell block immunocytochemistry provided a reliable strategy to examine oral mucosal epithelial disorders.  This approach presented a minimally invasive, highly accurate and non-technically demanding method for the surveillance of oral potentially malignant disorders and SCC.

The authors stated that this study had several potential drawbacks.  First, the relatively small sample size and the retrospective nature of the study design could hinder the applicability of the technique in a clinical setting.  Second, the study may have suffered from selection bias by only including clinically diagnosed cases of OLK; further prospective studies that include a wide variety of OPMDs are needed to support the implementation of this approach in daily diagnostic pathology practice.  Third, the investigation of additional molecular markers using cell blocks is recommended.

In a cost-utility study, Idrees et al (2022a) examined the diagnostic utility and associated cost of OLBC in the diagnosis of oral cancer and OPMDs.  A total of 284 patients with oral mucosal lesions were included.  OLBC samples were collected from all patients immediately before undergoing surgical biopsies.  A liquid-based cytology slide was prepared from each OLBC sample for cytological evaluation using the modified 2014 Bethesda cytology system.  The results and the cost were compared with the histopathological outcomes.  The level of agreement between the 2 approaches was very good (weighted kappa = 0.824).  The accuracy of OLBC in differentiating between the different diagnostic groups was 91.69 %, whereas the associated sensitivity and specificity were 79.23 % and 94.81 %, respectively.  The estimated cost of each OLBC sample was at least 26 % less than the cost of a single biopsy and more than 42 % less in cases of multiple biopsied lesions.  The authors concluded that the proposed modifications of the Bethesda system could be adopted as a standardized system for oral cytological assessment.  These researchers stated that these findings support OLBC as a reliable adjunct to surgical biopsy in the diagnosis of OPMDs; they stated that this his tool has potential for oral cancer-finding and surveillance programs.  Moreover, these researchers stated that although further refining of their modified Bethesda system is recommended to improve the associated sensitivity, they encouraged following this system in reporting oral brush findings to standardize the oral cytology results.

The authors stated that this study had several potential drawbacks.  First, the absence of a group of healthy volunteers with normal oral mucosa limited the ability to examine the use of this approach in differentiating between healthy and diseased individuals.  However, this group was not included because of ethical considerations.  Second, detailed clinical features of some lesions were not recorded, meaning it was not possible to link the clinical appearance of lesions with cytological outcomes.  Third, the lack of follow-up data limited the ability to build prognostic statistical models based on the cytology findings.  Fourth, the number of cases in each diagnostic group was relatively low in comparison to keratosis.  Although these numbers were adequate from a statistical perspective, this could be a potential source of bias.

Idrees et al (2022b) examined the effectiveness of using OLBC coupled with immune-stained cytology-derived cell blocks, quantified using machine-learning, in the diagnosis of oral lichen planus (OLP).  A total of 82 patients diagnosed clinically with either OLP or oral lichenoid lesion (OLL) were included.  OLBC samples were obtained from all patients before undergoing surgical biopsy.  Liquid-based cytology slides and cell blocks were prepared and examined by cytomorphology and immunocytochemistry for 4 antibodies (Ki-67, BAX, NF-κB-p65, and AMACR).  For comparison purposes, a sub-group of 31 matched surgical biopsy samples were selected randomly and examined by immunohistochemistry.  Patients were categorized according to their definitive diagnoses into OLP, OLL, and clinically lichenoid, but histopathologically dysplastic lesions (OEDL).  Machine-learning was used to provide automated quantification of positively stained protein expression.  Cytomorphological assessment was associated with an accuracy of 77.27 % in the distinction between OLP/OLL and OEDL.  A strong concordance of 92.5% (κ = 0.84) of immune-staining patterns was evident between cell blocks and tissue sections using machine-learning.  A diagnostic index using a Ki-67-based model was 100 % accurate in detecting lichenoid cases with epithelial dysplasia.  A BAX-based model demonstrated an accuracy of 92.16 %.  The accuracy of cytomorphological assessment was greatly improved when it was combined with BAX immuno-reactivity (95 %).  The authors concluded that cell blocks prepared from OLBC were reliable and minimally invasive alternatives to surgical biopsies to diagnose OLLs with epithelial dysplasia when combined with Ki-67 immuno-staining.  These investigators stated that machine-learning has a promising role in the automated quantification of immune-stained protein expression.

The authors stated that this study had several potential drawbacks.  First, the number of included cases in both cohorts was relatively low, which limited the ability to further validate the proposed techniques.  Second, the cohort did not include patients with oral lichenoid reactions; thus, it was not possible to examine the performance of this technique in a broad clinical setting.  Third, the thresholds used for staining intensities were optimized according to their staining protocols and reagents and there was a possibility that using antibodies from different vendors or different antibody dilutions could impact the accuracy of these thresholds.  These researchers stated that further investigations and optimizations are recommended when considering future studies.

Melanoma-Associated Antigens A (MAGE-A) Staining

Hartmann and colleagues (2015) stated that in oral cancer and in other tumor entities, melanoma-associated antigens are present. These antigens contribute to tumor progression and poor prognosis, and reduce the cytotoxicity of antineoplastic drugs. These researchers examined the diagnostic potential of these antigens in combination with oral brush biopsies.  They analyzed 72 oral brush biopsy specimens for melanoma-associated antigens A (MAGE-A) expression by immunocytologic staining with the MAGE-A 57B antibody.  A total of 24 healthy specimens, 15 lichen ruber cases, 18 leukoplakia cases, and 15 invasive carcinomas were studied.  Incisional biopsy served as the gold standard.  In total, 66 of 72 specimens (91.6 %) could be assessed; 12 of 15 (80 %) carcinomas stained positive for MAGE-A.  MAGE-A staining was detected in 4 of 51 non-malignant specimens, resulting in a false-positive rate of 7.8 %.  However, MAGE-A positive staining was significantly correlated with oral squamous cell carcinoma (p < 0.0005).  Sensitivity and specificity for MAGE-A staining and carcinoma were 80 % and 92.2 %, respectively.  The diagnostic accuracy was 89.4 %.  The authors concluded that the findings of this study indicated that oral brush biopsy with MAGE-A staining serves as an additional tool for use in oral cancer diagnosis.  They stated that these findings might help to facilitate an easier and more representative surveillance of the mucosa, particularly for large areas of altered mucosa.

Glucose Transporter (GLUT)-1 Staining

Brands and colleagues (2017) evaluated the sensitivity and specificity of an oral brush biopsy in combination with glucose transporter (GLUT)-1 staining in identifying pre-malignant and malignant lesions.  A total of 72 patients were included in the study; they were divided into 4 diagnostic subgroups (24 healthy, 15 carcinoma, 18 leukoplakia, 15 oral lichen planus).  Oral brush biopsies were taken and analyzed for GLUT-1 expression by immunocytologic staining.  Incisional biopsy served as the gold standard; 12 (80 %) of the 15 carcinomas, 9 (50 %) of the 18 leukoplakia, 9 (60 %) of the 15 oral lichen planus, and none of the healthy specimens stained positive for GLUT-1.  This resulted in a sensitivity rate of 80 % and a specificity rate of 68.42 %.  Diagnostic accuracy was 70.83 % based on the correct diagnoses in 51 of 72 patients.  The authors concluded that oral brush biopsy can easily be performed throughout the entire oral cavity, is non-invasive, and showed high sensitivity and specificity rates with conventional cytology or computer-assisted analysis.  Moreover, they noted that the significance of GLUT-1-specific staining with an oral brush biopsy is more limited than expected, but could be used as an additional tool in detecting malignant transformation in the oral cavity.  This was a relatively small study (n = 48 for carcinomas/leukoplakia/oral lichen planus); and the sensitivity, specificity, and diagnostic accuracy of oral brush biopsy with GLUT-1 staining were 80 %, 68.42 %, and 70.83 %, respectively.

Esophageal Brush Biopsy (WATS3D, formerly known as EndoCDx)

WATS3D, formerly known as EndoCDx, is a computer-assisted biopsy adjunct to standard forceps biopsy of the esophagus which increases the tissue area sampled and therefore, increases the yield of patients identified with abnormality in the esophagus.  Unlike standard cytology brushes that are typically soft and primarily designed to gently remove spontaneously exfoliated squamous cells in the esophagus, the WATS3D Biopsy is specifically designed to consistently sample deeper layers of the more firmly attached glandular epithelium found in Barrett’s esophagus.

Evidence for esophageal brush biopsy in Barrett's esophagus screening or surveillance is limited to diagnostic yield. However, whether this increase in diagnostic yield leads to improved patient outcomes is unclear.

Johanson et al (2011) conducted a study to evaluate the diagnostic yield of computer assisted analysis of an abrasive, transepithelial brush biopsy as an adjunct to forceps biopsy to increase detection of Barret's esophagus and esophageal dysplasia.  This was a multi-center prospective trial of patients being screened for Barrett's esophagus and esophageal dysplasia.  Each patient had 2 brush biopsies and then random 4-quadrant forceps biopsies every 1 to 2 cm of the esophagus.  All brush biopsies were examined with computer assistance by pathologists at CDx Laboratories, and all forceps biopsies were examined by the investigators' local pathologists.  Of 1,266 patients enrolled, 363 were diagnosed with Barrett's esophagus by forceps biopsy alone and 146 additional cases of Barrett's esophagus were identified by adding brush biopsy.  Among a subset of 848 patients with gastroesophageal reflux disease and no prior history of Barrett's esophagus, 150 were diagnosed with forceps biopsy and an additional 105 patients were diagnosed with Barrett's esophagus with brush biopsy.  Dysplasia was diagnosed in 16 patients by forceps biopsy (FB) alone, with an additional 14 cases detected by adding BB.  The authors concluded that these results suggested that adjunctive computer-assisted analysis of an abrasive brush biopsy has the potential to substantially improve the detection of Barrett's esophagus and dysplasia in screening populations.

Anandasabapathy et al (2011) studied whether the detection of dysplasia is improved by adding computer-assisted brush biopsy (EndoCDx) to 4-quadrant biopsy protocol.  Patients with a history of Barrett's esophagus with dysplasia scheduled for endoscopic surveillance were recruited from 4 academic medical centers.  Patients underwent brush biopsy followed by 4-quadrant biopsy every 1 to 2 cm.  The results from brush and forceps biopsy were reviewed independently by pathologists blinded to the other's results.  Among 151 patients enrolled (124 men, 27 women; mean age of 65 years), 117 (77.5 %) had forceps and brush-biopsy specimens adequate for interpretation.  The mean number of forceps biopsies was 11.9 (median of 10, range of 2 to 40) and brush biopsies was 2.0 (median of 2, range of 1 to 4).  The overall yield of forceps alone was 38 positive cases.  Brush biopsy added an additional 16 positive cases.  There were no significant differences in results among different centers, between standard versus jumbo forceps, or between forceps biopsies taken every 1 cm versus every 2 cm.  The authors concluded that these data suggested that computer-assisted brush biopsy is a useful adjunct to standard endoscopic surveillance regimens for the identification of dysplasia in Barrett's esophagus.

Guidelines on Barrett's esophagus from the American Gastroenterological Association, the American College of Gastroenterology, the British Society of Gastroenterology, and Cancer Council Australia have no recommendation for brush biopsy for screening or surveillance (AGA, 2011; Fitzgerald et al, 2014; Shaheen, et al., 2016; Tham, 2015; Whiteman et al, 2015). 

Kern and colleagues (2016) noted that patients with eosinophilic esophagitis (EoE) undergo multiple endoscopies with biopsy for both diagnosis and assessment of treatment response, which is inconvenient and costly.  Brush cytology has been examined in Barrett's esophagus (BE) to reduce the need for repeated endoscopic biopsies.  In a prospective study, these researchers evaluated the ability of brush cytology to detect mucosal eosinophilia in patients with EoE.  This study included adults with untreated and treated esophageal eosinophilia undergoing endoscopy at a tertiary-care center.  Participants received paired brushings and biopsies at the proximal and distal esophagus.  A blinded pathologist quantified the number of eosinophils and epithelial cells per high-power field (hpf) on the cytology slides.  The ratio of eosinophils/epithelial cells was used to normalize the cytology specimens for density of cells collected.  The main outcome measures were sensitivity and specificity of brush cytology, and correlation between cytology and histology.  A total of 28 patients were enrolled in this trial.  The average age of the cohort was 37.7 ± 10.4 years; 75 % of subjects were male.  The sensitivity of cytology was 67 to 69 % at the proximal esophagus and 70 to 72 % at the distal esophagus.  The specificity was 61 to 67 % proximally and 70 to 75 % distally.  Histology was not significantly correlated with the max ratio of eosinophils/epithelial cells per hpf or the absolute number of eosinophils on cytology slides.  The authors concluded that cytology using esophageal brushing has limited sensitivity and specificity for the detection of esophageal mucosal eosinophilia.  The presence of exudates on endoscopy increased the detection of eosinophilia, which could make cytology useful in pediatric EoE, which often has a more exudative presentation.  Moreover, they stated that diagnostic yield may improve with alternative acquisition techniques or the incorporation of eosinophil degranulation proteins.

Furthermore, National Comprehensive Cancer Network’s clinical practice guideline on “Esophageal and esophagogastric junction cancers” (Version 1.2017) does not mention computer-assisted brush-biopsy analysis as a management tool.

Vennalaganti and co-workers (2015) examined inter-observer agreement among pathologists in the diagnosis of Barrett's esophagus (BE)-associated dysplasia using the wide-area transepithelial sampling (WATS) computer-assisted analysis technique; WATS slides with varying degrees of BE dysplasia were randomly selected and distributed to 4 pathologists.  Each pathologist graded the slides as non-dysplastic BE (NDBE), low-grade dysplasia (LGD), or high-grade dysplasia/esophageal adenocarcinoma (HGD/esophageal adenocarcinoma [EAC]) and completed a standardized case report form (CRF) for each slide.  A total of 149 BE slides were evaluated in a blinded manner by 4 pathologists.  The slides included the following: ND (n = 109), LGD, and HGD/EAC (n = 40).  The overall mean kappa value for all 3 diagnoses for the 4 observers was calculated at 0.86 (95 % confidence interval [CI]: 0.75 to 0.97).  The kappa values (95 % CI) for HGD/EAC, indefinite for dysplasia (IND)/LGD, and NDBE were 0.95 (0.88 to 0.99), 0.74 (0.61 to 0.85), and 0.88 (0.81 to 0.94), respectively.  The authors concluded that diagnosis of BE and associated dysplasia using the WATS technique had very high inter-observer agreement.  This appeared to be significantly higher as compared with previously published data using standard histopathology.

Vennalaganti and colleagues (2018) noted that WATS with computer-assisted 3-D analysis is a sampling technique that combines abrasive brushing of the BE mucosa followed by neural network analysis to high-light abnormal-appearing cells.  These researchers performed a randomized trial of referred BE patients undergoing surveillance at 16 medical centers.  Subjects received either biopsy sampling followed by WATS or WATS followed by biopsy sampling.  The primary outcome was rate of detection of HGD/EAC using WATS in conjunction with biopsy sampling compared with biopsy sampling alone using standard histopathologic criteria.  Secondary aims included evaluating neoplasia detection rates based on the procedure order (WATS versus biopsy sampling first), of each procedure separately, and the additional time required for WATS.  A total of 160 patients (mean age of 63.4 years; 76 % men; 95 % white) completed the trial.  The median circumferential and maximal BE extents were 1.0 cm (inter-quartile range [IQR]: 0.0 to 5.0) and 4.0 cm (IQR, 2.0 to 8.0), respectively.  The diagnostic yield for biopsy sampling alone was as follows: HGD/EAC, 7 (4.4 %); LGD, 28 (17.5 NDBE, 106 (66.25 %); and no BE, 19 (11.9 %).  The addition of WATS to biopsy sampling yielded an additional 23 cases of HGD/EAC (absolute increase, 14.4 %; 95 % CI: 7.5 % to 21.2 %).  Among these 23 patients, 11 were classified by biopsy sampling as NDBE and 12 as LGD/ IND; 14 received biopsy sampling first and 9 WATS first (not significant) and most (n = 21; 91.7 %) had a prior dysplasia history; WATS added an average of 4.5 mins to the procedure.  The authors concluded that results of this multi-center, prospective, randomized trial demonstrated that the use of WATS in a referral BE population increased the detection of HGD/EAC.

In an editorial on the afore-mentioned study by Vennalaganti et al (2018), Canto and Montgomery (2018) stated that these researchers were to be congratulated for completing a prospective, relatively large, well-designed, and appropriately powered study.  However, the study had several drawback.  First, this study involved predominantly academic referral centers with enrichment of HGD / EAC, thus the results could not be generalized to a non-enriched community setting, where most BE patients undergoing surveillance have no dysplasia.  It was important to note that the majority (91 %) of the 23 patients with diagnoses of HGD / EAC by WATS sampling alone already had a prior diagnosis of dysplasia at study entry.  Hence, the true incremental benefit of WATS sampling with regard to increasing the dysplasia grade was uncertain.  Second, the performance characteristics of WATS were unknown and not formally studied.  Only the WATS-positive HGD / EAC slides were blindly reviewed by 2 pathologists, whereas ideally all cases should have been examined to determine the false-negative and false-positive rates.  Follow-up on a limited number of patients failed to confirm HGD / esophageal adenocarcinoma in only 5 of 9 patients, raising the concern for false-positive diagnoses by use of the WATS method.  One patient with a HGD / EAC diagnosis by biopsy received a diagnosis of LGD by WATS.  This was clearly a false-negative test result.  Third, the incremental cost of adding WATS sampling to random biopsy was unknown.  Fourth, the incremental benefit of WATS sampling in centers that routinely use advanced endoscopic imaging was unknown.  Finally, this study added WATS to random biopsy instead of comparing the 2 techniques.  Investigators are all looking for a way to avoid unnecessary random biopsy samples from non-dysplastic BE; a community-based RCT of WATS compared with the Seattle biopsy protocol, not as an adjunctive method but as the sole surveillance technique is needed.  These researchers stated that more questions arose from this interesting study.  Should the WATS 3-dimensional method plus the Seattle biopsy protocol be used routinely in every BE patient undergoing surveillance?  Which BE patients might be the best candidates for more aggressive tissue sampling?  Should it be reserved for long-segment BE?  The cancer risk for a given patient with non-dysplastic BE is quite low.  The most recent meta-analysis of cancer risk in BE patients produced a pooled estimate of 0.6 % per year.  Therefore, the majority of patients encountered in clinical practice are those without dysplasia.  Should WATS sampling be preferentially used in referral centers?  Or should any busy gastroenterologist who does not use advanced imaging techniques be a WATS user?  Perhaps the most important question that may limit adoption of the WATS technique is how physicians might reconcile their local pathologist’s diagnosis, expert pathology review, and the central pathology laboratory WATS diagnosis.  How can physicians treat their patients if there are discrepant diagnoses?  Are physicians ready to make the leap of faith and rely only on WATS?  The concerns and unanswered questions from the present study suggested -- not yet.

Responding to the editorial by Canto and Montgomery (2018), Goldblum et al (2018) stated that “The authors of this editorial make many reasonable statements regarding the limitations related to sampling of BE mucosa, including some of the limitations related to WATS.  In particular, the authors note a disagreement with regard to the diagnosis of dysplasia in some of the figures in our article.  In our opinion, the figures do depict dysplasia / adenocarcinoma as detailed in the figure legends.  Although we had several cases from which we could have potentially provided photomicrographs, similar criticisms could be levied at any of those figures, given the nature of interobserver variability in the recognition of dysplasia by pathologists, including expert GI pathologists.  As a matter of fact, Dr. Montgomery served as the first author for one of the most-quoted studies related to the difficulties of observer variability in BE-related dysplasia.  In that study, even after a consensus meeting establishing criteria for dysplasia, there was no significant increase in observer agreement, particularly at the low end of the spectrum (negative for dysplasia vs indefinite for dysplasia vs low-grade dysplasia).  As such, it is not surprising that there is disagreement related to the diagnosis depicted in our figures.  This remains the essence of the problem and of the potential opportunity offered by new techniques, including transepithelial sampling, for improvement in diagnostic interpretation.  What is not debatable is that 2 independent and blinded GI pathologists at the Cleveland Clinic confirmed that WATS detected 29 of 30 cases of HGD / early adenocarcinoma, whereas matching random biopsy detected only 7 of them.  Several of these patients with no dysplasia detected on random biopsy would not have had another surveillance endoscopy for 3 years.  Instead, owing to the WATS finding they were brought back, their WATS-detected HGD was confirmed on extensive biopsy, and they were successfully treated for their HGD.  The use of WATS in our routine GI clinical practices has corroborated this scenario numerous times and has made it clear to us that the current highly flawed random biopsy sampling protocol can be improved with wider sampling”.

In response, the editorialists (Canto and Montgomery, 2018) noted that “… However, our concerns regarding the WATS technique remain.  As the authors note, the interobserver variability in the assessment of Barrett’s esophagus (BE) samples is well known, as evidenced by one of our own studies from nearly 20 years ago and an elegant study by those same investigators last year specifically focusing on low-grade dysplasia.  We agree with the authors that disagreement in dysplasia grading remains part of the problem and that single images chosen from a full slide may not convey the subtleties of morphologic features to full advantage.  Some cytologic features may be apparent when the observer can view several planes of focus from the same cell cluster in a more 3-dimensional fashion, as is permitted during real-time microscopy with standard glass slides; such features are impossible to illustrate well in a single still image.  However, our larger remaining concern is that reactive basal glands sampled by the WATS technique evaluated out of their architectural context could readily be over-interpreted as high-grade dysplasia or carcinoma with excellent interobserver agreement between the computer and humans.  This, in turn, may result in over-treatment of patients if the WATS results are used to govern primary risk stratification and guide decision making.  Simply put, this important clinical trial still falls short because routine follow-up care was not planned as part of the study protocol to validate the diagnosis of WATS sampling.  Only 9 of the 23 patients with high-grade dysplasia /esophageal adenocarcinoma (HGD/EAC) on WATS had follow-up biopsies, and of those, 5 of 9 (56 %) of the diagnoses were not confirmed.  We still believe that more data should be gathered before WATS can be widely endorsed.  The results of this trial are still not generalizable to the average clinical practice outside academia.  Indeed, most of the patients detected only by WATS had already received diagnoses of HGD / EAC by outside examination of biopsy specimens.  In particular, we would like to see data comparing the WATS 3-dimensional technique alone versus standard 4-quadrant random biopsy alone for routine surveillance in populations with non-enriched Barrett’s esophagus in the community, where the majority of surveillance takes place and adherence to biopsy guidelines is less rigorous.  Regardless of our concerns, in the end, we applaud the authors for an excellent study that prompts discussion and increases interest in research in this area.  If the WATS method ultimately proves to reliably and accurately detect more early, treatable lesions in our patients, without the expense and effort of a rigid biopsy protocol, it would be a huge advance”.

In a multi-center, prospective trial, Gross and associates (2018) examined if WATS with 3-D computer-assisted analysis used adjunctively with forceps biopsy (FB) can increase the detection of BE and esophageal dysplasia (ED).  Patients screened for suspected BE and those with known BE undergoing surveillance were enrolled.  Patients at 25 community-based practices underwent WATS adjunctively to targeted FB and random 4-quadrant FB.  Of 4,203 patients, 594 were diagnosed with BE by FB alone, and 493 additional cases were detected by adding WATS, increasing the overall detection of BE by 83 % (493/594, 95 % CI: 74 % to 93 %); LGD was diagnosed in 26 patients by FB alone, and 23 additional cases were detected by adding WATS, increasing the detection of LGD by 88.5 % (23/26, 95 % CI: 48 % to 160 %).  The authors concluded that adjunctive use of WATS to FB significantly improved the detection of both BE and ED.  Sampling error, an inherent limitation associated with screening and surveillance, could be improved with WATS allowing better informed decisions to be made about the management and subsequent treatment of these patients.

The authors stated that this study had several drawbacks.  The order of WATS and FB was not randomized.  All the FB samples were obtained after WATS sampling.  However, the order of performing FB and WATS has been demonstrated in one study to not have any impact on the final results.  All specimens in this study were analyzed by 2 different sets of pathologists (WATS and FB) who were blinded from each other’s findings.  Although this analysis was conducted at a single-central laboratory, the data were comparable to studies in which WATS was analyzed at one laboratory and FB at another.  Although all investigators were instructed to sample only the tubular esophagus, this requirement was not independently monitored.  Furthermore, it may be difficult for gastroenterologists to definitively identify where a biopsy specimen may have come from in relation to the gastro-esophageal junction (GEJ) as there are no universally accepted validated landmarks that demarcate the distal extent of the esophagus.  Studies in BE patients have used the proximal extent of the gastric folds as the landmark for the GEJ despite the fact that it is a dynamic structure whose position changes with respiration, gut motor activity, and the degree of distention of the esophagus and stomach.  Thus, given these limitations, it was likely that some patients in this study diagnosed with BE, especially those with ultra-short BE, had in fact intestinal metaplasia of the cardia, which was thought to carry significantly less risk of cancer development than traditional BE.  These drawbacks may be overcome by ensuring gastroenterologists follow published guidelines for sampling suspected BE, and accurately assessing the extent of BE on endoscopy.  Measuring both the circumferential extent (C) and the maximum extent (M) (Prague C and M criteria) increased the accuracy in determining the length of intestinal metaplasia in the columnar-lined esophagus and helped identify those at greater risk for cancer.  The authors believed that the increased detection of disease will allow better informed decisions to be made about the management and subsequent treatment of these patients.

Furthermore, there is a clinical trial on “The Analysis of WATS3D (Wide Area Transepithelial Sample Biopsy With 3-Dimensional Computer-Assisted Analysis) Increased Yield of Barrett's Esophagus and Esophageal Dysplasia” that is currently recruiting patients (last updated January 25, 2018).  

Smith et al (2019) noted that the 4-quadrant FB protocol for identifying BE and ED suffers from poor sensitivity due to significant sampling error.  In a prospective, multi-center trial, these investigators examined the benefit of WATS used adjunctively to the combination of random and targeted FB in the detection of ED, and as a secondary outcome, BE.  Community endoscopists at 21 sites utilized WATS as an adjunct to both targeted and random FB in patients undergoing BE screening and surveillance.  Investigators alternated taking FB and WATS samples first.  WATS specimens were analyzed at CDx Diagnostics while FB samples were analyzed by each site's regular pathologists.  Data were de-identified and then aggregated for analysis.  Of 12,899 patients enrolled, FB identified 88 cases of ED, and WATS detected an additional 213 cases missed by FB.  These 213 cases represented an absolute increase of 1.65 %, raising the yield from 0.68 % to 2.33 %.  Adding WATS to FB increased the overall detection of ED by 242 % (95 % CI: 191 % to 315 %).  Fewer than 61 patients needed to be tested with WATS to identify an additional case of ED.  The combination of random and targeted FB identified 1,684 cases of BE, and WATS detected an additional 2,570 BE cases.  The absolute incremental yield of adding WATS to FB was 19.9 %, increasing the rate of detection from 13.1 % to 33 %.  Adding WATS to FB increased the overall detection of BE by 153 % (95 % CI: 144 % to 162 %).  The number needed to test with WATS in order to detect an additional case of BE was 5.  Whether FB or WATS was done first did not impact the results.  In this study, comprised of the largest series of patients evaluated with WATS, adjunctive use of the technique with targeted and random FB markedly improved the detection of both ED and BE.  These researchers stated that the findings of this study suggested that by testing a larger portion of the esophagus with WATS that would not ordinarily be sampled by FB, high risk patients undergoing endoscopic surveillance programs for the diagnosis of BE neoplasia could be more readily identified, thereby potentially improving their management and eventual outcome.

The authors stated that this study had several limitations.  Although routine screening for BE in women is not recommended, women accounted for 61 % of patients in this study.  Data regarding women in this study who would be potential candidates for BE screening by exhibiting multiple risk factors for BE or EAC (greater than 50 years of age, Caucasian race, chronic or frequent GERD, central obesity, waist circumference greater than 88 cm, waist to hip ratio greater than 0.8, current or past history of smoking, a confirmed family history of BE or EAC) was not collected.  It may be argued that the biological behavior of WATS-detected BE or ED may differ from disease detected by FB.  While the WATS computer assisted the pathologist in the location of potentially abnormal cells within the thick WATS specimens, once identified, they were ultimately interpreted and reported based upon standard pathologic diagnostic criteria that were considered pathognomonic for the disease.  This was depicted via side by side pathology images from WATS and FB respectively in patients with BE, LGD, and HGD.  Furthermore, blinded independent cytopathologists confirmed all cases of ED that were detected with WATS.  The progression rate of a FB-negative / WATS-positive LGD to HGD / EAC would provide additional confirmation that the biological behavior of a WATS-detected versus FB-detected dysplastic cell is the same.  The data from a separate registry study demonstrating that the progression rates of WATS-detected BE and of WATS-detected LGD to HGD / EAC are comparable to the progression rates of FB-detected BE and of FB-detected LGD to HGD / EAC is currently being prepared for publication by the authors.  Although investigators were instructed to sample visible tongues of columnar mucosa in the tubular esophagus, investigators were not monitored, and the number and site of biopsies taken at each endoscopy were left to the discretion of the endoscopist.  It was likely however, that in this registry study, adherence to endoscopic biopsy guidelines were followed by the great majority of endoscopists as they were verbally instructed to follow them prior to starting the study and the overwhelming majority of patients in this study did not exhibit long segment BE, a characteristic that is most associated with non-adherence to biopsy guidelines.  Furthermore, the purpose of this study was to determine the benefits of adding WATS to the FB protocol actually utilized in practice by community-based endoscopists nationwide and not to the Seattle biopsy protocol.  While clinicians were instructed to only sample the tubular esophagus, in patients with short segments of esophageal columnar epithelium, locating the gastroesophageal junction, identified as the most proximal extent of the gastric folds, may be difficult as its position is affected by respiration and gut motor activity.  Thus, it was likely that some patients in this study diagnosed with BE by WATS had in fact, cardia intestinal metaplasia (CIM).  Sampling cases of BE with less than a 1 cm of metaplasia is problematic as there is significant inter-observer and intra-observer variation in the estimation of BE length by probably as much as 1.0 cm.  Finally, this study, which examined the use of WATS as an adjunct to the combination of targeted and random FB was also not designed to address the question of whether WATS alone can substitute for, or is more effective than random FB in the detection of BE and BE-associated dysplasia.  FB detected 641 cases of BE and 18 cases of ED including 5 patients with HGD / EAC not identified by WATS.  Since FB was utilized not only for random 4-quadrant sampling but was the sole technique used to target visible mucosal abnormality, FB, not surprisingly, identified some patients with BE, ED and HGD / EAC that were not detected by WATS.  By contrast, WATS was used to test large areas of the esophagus, which would have remained untested by both targeted and random FB.  Thus, increased adjunctive yield for BE and ED / neoplasia is the metric that is most meaningful.  These investigators clearly demonstrated that the use of WATS as an adjunct to both targeted and random FB does significantly improved the detection of ED as well as BE, in agreement with previously published studies.

Raphael et al (2019) reported on a retrospective observational cohort study from January 2017 to December 2018 of 138 consecutive patients at a tertiary care academic referral center who underwent an examination that consists of high-definition white light endoscopy (HDWLE), narrow-band imaging (NBI), volumetric laser endomicroscopy (VLE), and Seattle protocol (SP) biopsies (collectively termed HDWLE-NBI-VLE-SP examination). Raised lesions were removed by endoscopic resection. Areas suspicious for dysplasia on NBI and VLE were biopsied. This was followed by random biopsies and WATS-3D brush biopsies. Thirty-five cases (25% of the total) were identified as some degree of dysplasia on the HDWLE-NBI-VLE-SP examination. Adjunctive use of WATS-3D yielded an additional 12 new cases of dysplasia (9 with crypt dysplasia and 3 with low-grade dysplasia [LGD]), for added yield of 34.3% (=12/35, 95% confidence interval 14.6%-62.2%). When restricting the analysis to LGD and higher, given the unclear significance of crypt dysplasia, 21 dysplastic cases (15% of the total cases) were identified by HDWLE-NBI-VLE-SP, while WATS-3D found 4 additional new cases (3 with LGD and 1 with high-grade dysplasia) for an added yield of 19% (=4/21, 95% confidence interval 0.6%-45.7%). The investigators noted that patients noted to have dysplasia solely on WATS-3D analysis did not undergo subsequent confirmation of this dysplasia by standard histological diagnosis, and thus, there was no external gold standard to compare the positive WATS-3D result to. The investigators concluded that "[f]urther prospective studies are warranted to confirm our results and to better delineate the significance of a diagnosis of crypt dysplasia."

Deemester et al (2019) presented an abstract summarizing a randomized controlled trial comparing standard forceps biopsies to wide-area transepithelial sampling brush for finding intestinal metaplasia and dysplasia in the esophagus and gastroesophageal junction. Patients scheduled to undergo routine upper endoscopy for foregut or esophageal symptoms were enrolled. Patients undergoing surveillance for Barrett's esophagus with no dysplasia or low-grade dysplasia were candidates for participation, but patients with known high-grade dysplasia or adenocarcinoma or with a history of prior endoscopic resection or ablation for these conditions were excluded from participation. Patients were randomized prior to starting the procedure. Each patient received a randomization code at the time of randomization.  At endoscopy, all patients were initially assessed for the presence of an endoscopic suspicious lesion using white light and where appropriate narrow band imaging or similar enhanced imaging techniques. All suspicious lesions underwent targeted biopsy first, and then either 4-Quadrant Random Forceps Biopsy or WATS biopsies of the GEJ and if present the columnar-lined esophagus based on the assigned randomization away from the area of targeted biopsies. A biopsy was obtained from the antrum in each patient to assess for H. pylori infection and the presence of intestinal metaplasia. Targeted forceps biopsies of any endoscopic suspicious area were placed in a separate pathology bottle from those obtained from 4-Quadrant Random Forceps Biopsy and analyzed separately. WATS specimens were analyzed by CDx Diagnostics. Investigators shipped the WATS specimens to CDx Diagnostics in accordance with CDx's instructions. Forceps biopsies were analyzed by institution's pathology department and by the pathology department of each additional site participating in the study per standard protocol. The investigator determined appropriate follow-up of patients with and without IM or dysplasia detected by WATS or FB per standard individual and / or institution protocol. Biopsies with intestinal metaplasia or dysplasia may have been reviewed by a central pathologist to confirm the original pathologic interpretation when there is a discrepancy between WATS and FB that is greater than 10%. The primary prespecified outcome measure was the diagnostic yield of intestinal metaplasia (IM) from WATS biopsies compared to Forceps biopsies. There were 1002 patients enrolled at 9 centers. A total of 509 patients had biopsies and 493 had WATS. A columnar-lined esophagus (CLE) of any length was seen in 282 patients, while in 720 patients there was no CLE and the biopsy or WATS was from a normal or irregular appearing gastroesophageal junction (GEJ). The median length of CLE when present was 3 cm. There was no statistically significant difference between biopsy and WATS in the diagnostic yield of IM, the prespecified primary study endpoint. The overall frequency of finding IM by biopsy was 19.45% and by WATS 22.72%, P = 0.2. The investigators noted, however, several findings in post-hoc analysis. Patients without a prior history of IM, biopsy and WATS found IM with similar frequency overall, but WATS found significantly more IM in patients with any endoscopically visible length of CLE. Biopsy found one cancer, and low-grade dysplasia was found in one patient each with biopsy and WATS. In the 185 patients that had their endoscopy for follow-up of Barrett's or ablation there was no difference in the frequency of IM detection for biopsy vs WATS, and was similar in patients with < 3 cm CLE and in those with ≥ 3 cm CLE. Dysplasia or cancer was found in 5 patients in this group, 2 by WATS and 3 by biopsy. The investigators concluded that both biopsy and WATS detect a similar frequency of IM overall; however, WATS was over twice as likely as biopsies to find IM in patients without a history of IM who had a CLE on endoscopy. In patients undergoing surveillance for Barrett's or follow-up after ablation both WATS and biopsy showed IM and dysplasia with similar frequency. The authors concluded that these findings suggest that WATS can be used instead of biopsies of the GEJ and esophagus with similar or improved efficacy at detecting IM and dysplasia.

An ASGE guideline on screening and surveillance of Barrett's esophagus (Qumseya, et al., 2019) states: "In patients with known or suspected BE, we suggest using WATS-3D in addition to WLE with Seattle protocol biopsy sampling compared with WLE with Seattle protocol biopsy sampling alone." The ASGE assessment rated the evidence for this recommendation as low quality using the GRADE approach. Low quality evidence means that their confidence in the estimate of the effect is limited, and that the true effect may be substantially different from the estimate of the effect. This implies that further research is very likely to have an impact on our confidence in the estimate of the effect and is likely to change the estimate. The randomized controlled clinical trials included in the ASGE assessment were downgraded due to risk of bias and inconsistency judged to be serious. The observational study examining adverse events included in the assessment was judged to have a serious risk of bias. The assessment explained that the dysplasia definition varied across studies; some studies included low grade dysplasia (LGD), whereas others did not. All the studies were funded by the manufacturer, CDx Diagnostics. The assessment noted that the increase in dysplasia detection reported on WATS-3D may be largely related to LGD, and that, in a subanalysis of four of the studies, the absolute increase in LGD detection was 1.8%. The assessment stated, however, that the question remains of what LGD means on cytology compared with LGD dysplasia on histology. Another related question is the diagnosis of crypt dysplasia reported on WATS specimens. The assessment cited data from Shaheen, et al. (2018) reporting on a progression rate of crypt dysplasia to HGD/EAC of 2.1% per patient year, which was very similar to the incidence rate of 2.2% reported in a metaanalysis assessing disease progression rates in Barrett;s esophagus patients with LGD. The assessment stated that this suggests that patients with the diagnosis of crypt dysplasia may be at a higher risk for progression and "future prospective studies should define the natural history of this entity before management plans are altered based on this diagnosis." The ASGE guideline panel initially made no recommendation for WATS-3D at the face-to-face meeting. After a complete review of additional published literature (including data on adverse events) and an additional phone conference, the panel made a conditional recommendation for the use of WATS-3D in addition to WLE with Seattle protocol biopsy sampling. GRADE recommendations are more likely to be conditional/weak rather than strong when the certainty in evidence is low when there is a close balance between desirable and undesirable consequences (Siemieniuk and Guyatt, 2020). In addition, a GRADE recommendation is more likely to conditional/weak when there is substantial variation or uncertainty in patient values and preferences, and when interventions require considerable resources. 

The ASGE’s guideline on “Screening and surveillance of Barrett’s esophagus” (Qumseya et al, 2019) states that “The panel initially made no recommendation for WATS-3D at the face-to-face meeting.  After a complete review of additional published literature (including data on AEs) and an additional phone conference, the panel made a conditional recommendation for the use of WATS-3D in addition to WLE with Seattle protocol biopsy sampling. 

  • In patients with known or suspected BE, we suggest using WATS-3D in addition to WLE with Seattle protocol biopsy sampling compared with WLE with Seattle protocol biopsy sampling alone (conditional recommendation, low quality of evidence).

Kaul et al (2020) noted that sampling error during screening and surveillance endoscopy is a well-recognized problem; and WATS3D, used adjunctively to forceps biopsy (FB), has been shown to increase the detection of BE and BE-associated neoplasia.  These researchers examined the clinical utility of WATS3D and its impact on the management of patients with BE and dysplasia.  Between 2013 and 2018, a total of 432 consecutive patients who had a WATS3D-positive and an accompanying FB-negative result were identified.  Physicians were contacted to determine if the WATS3D result impacted their decision to enroll patients in surveillance or increase the frequency of surveillance, recommend ablation, and/or initiate or increase the dose of proton pump inhibitors (PPIs).  WATS3D directly impacted the management of 97.8 % of 317 BE patients; 96.2 % were enrolled in surveillance and 60.2 % were started on PPIs or their dose was increased.  WATS3D impacted the management of 94.9 % and 94.1 % of the 98 low-grade dysplasia (LGD) and 17 high-grade dysplasia (HGD) patients, respectively.  As a result of WATS3D, 33.7 % of LGD and 70.6 % of HGD patients underwent endoscopic therapy.  More than 37 % of all dysplasia patients were enrolled in a surveillance program, and nearly 30 % were scheduled to be surveilled more frequently.  Furthermore, PPIs were either initiated, or the dose was increased in more than 54 % of all dysplasia patients.  The authors demonstrated that WATS3D has high clinical utility.  By prompting physicians to change their clinical management in patients with negative FB results, WATS3D, used adjunctively to FB, directly impacted patient management, and improved patient outcomes.

Kumar et al (2020) stated that WATS is a new technique that uses an abrasive brush to obtain samples from a larger surface area of the esophagus.  Studies have shown promising results that WATS in adjunct to FB increases the detection rate of BE as well as esophageal dysplasia (ED).  In a systematic review and meta-analysis, these researchers compared the detection rates of BE and ED between FB and WATS in adjunct to FB.  They carried out a literature search using electronic databases, including PubMed, Embase, Scopus, Cochrane and CINAHL from inception to April 26, 2020.  A meta-analysis comparing detection rates of WATS in adjunct to FB versus FB using the random-effects model was performed using RevMan V.5.3.  Pooled data from 20,392 endoscopies across 11 studies showed an absolute increase in detection of 16 % (95 % confidence interval [CI]: 0.10 % to 0.22 %, p < 0.00001).  A relative increase of 1.62 was observed in detection rates of BE (95 % CI: 1.28 to 2.05, p < 0.0001) when WATS was used with FB with the number needed to test (NNT) of 6.1 patients.  For ED, a 2 % absolute increase (95 % CI: 0.01 to 0.03, p = 0.001) in additional diagnostic yield from WATS.  A relative increase of 2.05 was observed in the detection rate of ED (95 % CI: 1.42 to 2.98, p = 0.0001) yielding an NNT of 50 patients.  The authors concluded that the findings of this study showed that WATS, as an adjunct to FB, improved both the absolute detection rate and relative detection rate of both BE and ED as compared to FB alone.  Moreover, these researchers stated that although current data are promising, further prospective, international, multi-center studies are needed before widespread usage of WATS is adopted.

The authors stated that this study had several drawbacks.  First, all the studies were from the U.S.  Lack of studies from other countries meant that generalizability outside the U.S. is still unclear until further studies are carried out involving non-U.S. population groups.  Second, these investigators did not include studies published in other languages and this might have resulted in omittance of certain studies.  Third, most of the studies were performed at tertiary-level centers by expert gastroenterologists; thus, they could not generalize the findings to general practice yet.  Fourth, inter-user variability needs to be evaluated before adopting this technique universally.  Lastly, all the studies included were non-randomized and open-labelled studies.

Agha et al (2021) noted that BE is a pre-malignant condition diagnosed using systematic 4-quadrant FB during endoscopy.  This method is fraught with errors due to the randomness of sampling and variability among operators.  Wide-area transepithelial sampling with WATS3D is an emerging technique used to collect esophageal samples.  In a retrospective, observational, cohort study, these researchers examined WATS3D as a diagnostic tool for detecting BE in addition to FB, compared to FB alone.  This trial included patients who underwent screening for BE with WATS3D and FB between January 2015 and January 2019 across 3 endoscopy centers in Wichita, Kansas.  The FB specimens were reviewed by community pathologists, while the WATS3D samples were sent to CDX Technology Labs, NY.  A total of 108 patients were screened for BE using both modalities concurrently.  FB and WATS3D detected 62 (57.4 %) and 83 (76 %) cases of BE, respectively.  The absolute difference of 21 cases (18.6 %) of BE was attributed to the addition of WATS3D.  The number needed to test with WATS3D was 5.  These investigators divided the sample into 4 groups to compare the agreement across all groups: (FB-; WATS3D+), (FB-; WATS3D-), (FB+; WATS3D+), and (FB+ and WATS3D-).  Overall agreement by kappa statistic was 0.74.  The authors concluded that the WATS3D identified 21 cases of BE missed by FB.  Using WATS3D in addition to FB increased the yield of BE during surveillance endoscopy, with no increase in complications.  These researchers stated that the main drawbacks of this study included its retrospective design, and the possible variation among the 3 gastroenterologists in sampling. 

Furthermore, UpToDate reviews on “Barrett's esophagus: Epidemiology, clinical manifestations, and diagnosis” (Spechler, 2021a) and “Barrett's esophagus: Surveillance and management” (Spechler, 2021b) do not mention WATS3D / esophageal brush biopsy as a management tool.

Codipilly et al (2022) stated that FB is currently recommended for surveillance in BE; however, this approach is limited by sampling error and lack of compliance.  Wide-area transepithelial sampling with 3-dimensional analysis (WATS3D; CDx Diagnostics, Suffern, NY) is reported to increase BE dysplasia detection.  In a systematic review and meta-analysis, these investigators examined the incremental yield and clinical significance of WATS3D for dysplasia detection over FB.  They queried major scientific databases for studies using WATS3D and FB from 2000 to 2020.  The primary outcome was the incremental yield of WATS3D-detected dysplasia (defined as a composite of IND, LGD, HGD, and EAC) over FB.  Secondary outcomes were incremental yields of HGD/EAC and rate of reconfirmation of WATS3D dysplasia on subsequent FB.  Meta-analysis of 7 eligible studies demonstrated that FB diagnosed dysplasia in 15.9 % of cases, whereas the incremental yield with WATS3D was 7.2 % (95 % CI: 3.9 % to 11.5 %; I2 = 92.1 %).  Meta-analysis of 6 studies demonstrated that FB diagnosed HGD/EAC in 2.3 % of patients, whereas the incremental yield with WATS3D was 2.1 % (95 % CI: 0.4 % to 5.3 %; I2 = 92.7 %).  Notably, WATS3D was negative in 62.5 % of cases where FB identified dysplasia; 2 studies reported re-confirmation of WATS3D dysplasia with FB histology in only 20 patients.  The authors concluded that WATS3D increased dysplasia detection; however, the clinical significance of this increased dysplasia detection remains uncertain.  These investigators stated that data from endoscopic follow-up to determine FB histology in patients with dysplasia based solely on WATS3D are needed to ascertain the optimal clinical application and significance of WATS3D-only dysplasia.

Shaheen and associates (2022) stated that wide-area transepithelial sampling with WATS3D is used as an adjunct to FB sampling in BE.  BE-associated crypt dysplasia (CD), which can be detected by WATS3D, involves crypts but not surface epithelium.  The risk of neoplastic progression of CD has never been evaluated.  The prognosis of WATS3D-diagnosed non-dysplastic BE (NDBE) and LGD is also unknown.  In a retrospective analysis, these researchers examined the risk of progression of WATS3D-reported NDBE, CD, and LGD with HGD or EAC.  They analyzed patients who underwent WATS3D in routine care.  Eligible patients had 2 WATS3D greater than or equal to 12 months apart.  Patients were categorized by the initial WATS3D finding as NDBE, CD, or LGD.  Patient-years of observation were calculated by multiplying the mean follow-up by the number of patients.  Progression, defined as a subsequent finding of HGD/EAC on FB sampling, was assessed.  The crude progression rate was calculated, and Kaplan-Meier analysis compared progression rates stratified by baseline histology.  Bi-variate analysis identified progression risk factors.  Of 151,224 WATS3D cases, 43,145 (29 %) had BE.  Of these, 4,545 patients had 2 WATS3D separated by greater than or equal to 12 months.  The mean follow-up was 1.97 years (range of 1.0 to 6.42).  In patients with baseline NDBE, progression was 0.08 % per patient-year (95 % CI: 0.02 % to 0.14 %).  Progression of baseline CD was significantly higher, at 1.42 % per patient-year (95 % CI: 0 % to 3.01 %).  For baseline LGD, progression was 5.79 % per patient-year (95 % CI: 1.02 % to 10.55 %).  Other risk factors for progression were increasing age and BE segment length.  The authors concluded that NDBE found on WATS3D has a very low risk of progression.  CD reported on WATS3D appeared to be a neoplastic precursor lesion, with a risk of progression in this study significantly higher than NDBE but lower than LGD.  Moreover, these researchers stated that the clinical utility of CD requires further investigation.

In an editorial that accompanied the study by Shaheen et al (2022), Codipilly and Iyer (2022) stated that although this was the 1st comprehensive study on FB-confirmed WATS-3D outcomes, several limitations need to be addressed.  Despite the inclusion of more than 4,000 patients, the original WATS-3D cohort consisted of 38,759 patients with IM (entered into a CDx commercial database), so the vast majority did not undergo a 2nd round of WATS-3D biopsies.  Whether this represented some form of selection bias, because patients with 2 WATS-3D biopsies appeared to have longer BE segments compared with those excluded and therefore may have been considered at higher risk by their treating clinician, is unclear; however, this may have artificially increased progression rates.  Baseline histologic features and final progression histologic features were also not confirmed by expert GI pathologists.  Given the known substantial proportion of down-grading of community LGD diagnosis upon expert review, and the lack of consensus among pathologists on a diagnosis of CD, these estimates should be interpreted with caution.  Furthermore, these editorialists stated that used as an adjunct to traditional FBs, WATS-3D may identify progression that would otherwise be missed based on FB alone, with progression estimates of WATS-3D NDBE and LGD approximating or exceeding those of FB.  Although prospective data on larger cohorts and the outcomes in those with WATS-3D-only LGD/HGD (with FB-negative histologic features) are needed to fully elucidate the role of WATS-3D in BE surveillance, this study highlighted some of the gaps that need to be filled for the firm inclusion of WATS-3D in the available therapeutic options for BE management.

DeMeester et al (2022) noted that intestinal metaplasia (IM) in the esophagus is a potentially pre-malignant mucosal change.  These researchers compared the frequency of IM detection during upper endoscopy by forceps biopsy sampling (FB) versus wide-area transepithelial sampling (WATS) brush.  Patients presenting for upper endoscopy for fore-gut symptoms or surveillance of Barrett’s esophagus (BE) at 9 centers in the U.S. were randomized to either FB or WATS.  Of 1,002 patients, FB was done in 505 and WATS in 497.  The overall frequency of finding IM was 21 % and was similar with FB (19.6 %) and WATS (22.7 %, p = 0.2).  Low-grade dysplasia (LGD) was found in 8 patients.  No patient had high-grade dysplasia (HGD).  There was no difference in detection of dysplasia between FB and WATS.  In patients with no history of IM, WATS found significantly more IM compared with FB when a columnar-lined esophagus (CLE) was present (32.4 % with WATS versus 15.2 % with FB, p = 0.004).  In 184 patients with known BE, FB and WATS found IM with similar frequency (38.5 % FB versus 41.9 % WATS, p = 0.6) with no difference in short- or long-segment BE.  The authors concluded that overall, FB and WATS detected a similar frequency of IM and dysplasia.  WATS was twice as likely as FB to find IM in patients without a history of BE who had CLE on endoscopy.  In patients with known BE, WATS and FB showed IM and dysplasia with similar frequency.  These findings suggested that WATS can be used instead of FB with similar or improved effectiveness at detecting IM and dysplasia.

The authors stated that this study has both strengths and weaknesses.  It was strengthened by the large number of patients from multiple centers across the U.S and the inclusion of multiple ethnicities.  However, most patients were women with no history of IM, and this influenced the frequency of finding IM.  Because the purpose of this study was to compare FB and WATS for finding IM, the absolute frequency of IM in the study population was not a critical issue, and the power analysis took this into consideration, using an estimated population prevalence of IM of 10 %.  This study was also strengthened by inclusion of patients with and without known esophageal IM.  This allowed a comparison of FB and WATS for finding IM de-novo and for confirming its presence in patients previously shown to have IM.  A weakness in this study was that only 30 patients with long-segment BE underwent surveillance.  In these patients, 14 had FB and 16 had WATS, and although both techniques found IM and dysplasia with a similar frequency, this should be studied further in a larger group of patients given the potential for a Type II error.  Furthermore, in this series there was a paucity of patients with dysplasia, and future studies in a larger group of patients with dysplasia may allow better assessment of WATS versus FB in this setting.

Fatima et al (2022) stated that BE and dysplasia are often missed by Seattle protocol biopsies (SPB).  WATS-3D with SPB improves detection in treatment-naive patients.  In a retrospective, observational, cross-sectional study, these investigators determined to what extent WATS-3D adds to SPB in the detection of NDBE and dysplasia in patients undergoing post-endoscopic eradication therapy (EET).  This trial included patients who presented for post-EET surveillance with SPB and WATS-3D sampling from April 2019 to February 2020.  BE patients with no previous EET were excluded.  For the outcomes of NDBE and any dysplastic/neoplastic finding, these researchers calculated both relative and absolute increases in yield by WATS-3D over SBP.  In 78 patients [mean age 68 ± 10.4 years, 66 (84.6 %) men], the prevalence of NDBE, any dysplastic/neoplastic finding, and any abnormality (NDBE or dysplasia/neoplasia) were 53.85 %, 10.26 %, and 55.13 %, respectively.  The absolute increase in yield of NDBE with WATS-3D over SPB was 26.9 % (95 % CI: 17.95 % to 37.18 %), with the number needed to treat (NNT) 3.71 (95 % CI: 2.69 to 5.57) and a relative increase in yield of 100 % (95 % CI: 53.33 % to 188.25 %).  For dysplasia/neoplasia, the absolute increase in yield was 6.4 % (95 % CI: 1.28 % to 12.82 %), NNT 15.6 (95 % CI: 7.8 to 78.0), and relative increase of 167 % (95 % CI: 33.33 % to infinity).  For any abnormal finding, the absolute increase in yield was 26.9 % (95 % CI: 16.67 % to 37.18 %), NNT 3.71 (95 % CI: 2.69 to 6.00), and relative increase in yield 95 % (95 % CI: 50 % to 176.92 %).  The authors concluded that the adjunctive use of WATS-3D with SPB can be a promising tool to increase detection of BE in post-ablation patients.  However, more extensive, prospective, randomized studies are needed to further validate these findings in academic and community settings.  Furthermore, whether WATS-3D has the potential to be used alone in the future will require further studies that compare the use of WATS in conjunction with SPB versus SPB alone versus WATS-3D alone, to address the question of whether WATS-3D can be a possible substitute for SPB in certain situations.

The authors stated that this study had several drawbacks.  First, it included a small number of patients (n = 78) from 1 center and so was not adequately powered to reach significance.  Second, it was based in a single center in a tertiary academic institution, and hence the results cannot be generalizable to community-based practices.  Third, this was a retrospective analysis, with the inherent limitations of that study design, while neither the Indiana University pathologists nor the WATS-3D pathologists were blinded to the baseline pathology findings.  Furthermore, SPB was performed before WATS-3D in all cases, and one of the endoscopists sampled only squamo-columnar junction and cardia.  Finally, this trial only looked at WATS-3D as an adjunct tool; but could not answer the question of whether WATS-3D can be used on its own as a substitute for SPB in the detection of BE in post-ablation patients.

Puthenpura et al (2022) noted that BE, a precursor for EAC, is defined as salmon-colored mucosa extending more than 1 cm proximal to the gastro-esophageal junction with histological evidence of IM.  The actual risk of EAC in NDBE is low with an annual incidence of 0.3 %.  The mainstay in the management of NDBE is control of gastro-esophageal reflux disease (GERD) along with enrollment in surveillance programs.  The current recommendation for surveillance is high-definition white light endoscopy 4-quadrant biopsies every 2 cm (or 1 cm in known or suspected dysplasia) followed by biopsy of mucosal irregularity (nodules, ulcers, or other visible lesions) performed every 3 to 5 years.  Challenges to surveillance include missed cancers, suboptimal adherence to surveillance guidelines, and lack of strong evidence for efficacy.  There is minimal role for endoscopic eradication therapy in NDBE.  The role for enhanced imaging techniques, artificial intelligence, and risk prediction models using clinical data and molecular markers is evolving.  Moreover, the authors stated that recently, WATS-3D has been shown to increase dysplasia detection; however, the clinical significance of this increased dysplasia detection remains uncertain.  These researchers stated that further investigations into optimization of intervention and observation will aid in refining the current guidelines for management of NDBE and prevent progression to advanced EAC.

Choi et al (2022) stated that a variety of biomarkers and assays, such as p53 immunostaining, WATS3D, mutational load analysis (BarreGen), fluorescence in situ hybridization (FISH), and DNA content abnormalities as detected by DNA flow cytometry have been extensively evaluated.  Although none of these studies has comprehensively examined the potential utility of these biomarkers in reducing mortality from EAC compared with the current surveillance standards, they have demonstrated a potential benefit when used in combination with histologic findings to aid in the diagnosis and/or risk stratification of BE and dysplasia.  These investigators provided an overview of these biomarkers and tests that appear most promising based on the availability of multiple published results and/or on their commercial availability.  The authors noted that there are several limitations with WATS3D.  First, although a study examining the inter-observer agreement among pathologists using WATS3D found substantial agreement for LGD, HGD, and no dysplasia, the diagnostic criteria used in WATS3D have not been independently tested.  Second, the data used to construct the algorithm that creates three-dimensional (3D) images of esophageal glands and adequacy criteria used for this test are not well delineated.  Third, regenerative epithelial changes in deep glands could be easily mis-interpreted as HGD on a single plane of analysis as in WATS3D, an issue that merits additional evaluation.  Fourth, this commercial test is interpreted by a limited group of pathologists.  Independent reproduction and evaluation of WATS3D diagnoses in academic settings with expert reviews of all FB by specialized GI pathologists (by all means not infallible) would go a long way to address some of these criticisms.  Fifth, whether the progression rate of dysplasia detected by WATS3D differs from that of dysplasia identified by FB and microscopy alone remains to be established.

Qumseya et al (2022) stated that wide-area transepithelial sampling (WATS) is an emerging technique that may increase dysplasia detection in BE.  In a systematic review and meta-analysis, these investigators examined the additional yield of WATS to Seattle protocol forceps biopsy sampling (FB) in patients who underwent surveillance for BE.  They searched PubMed, Embase, Web of science, and the Cochrane library, ending in January 2021.  The primary outcomes were the relative and absolute increase in dysplasia detection when adding WATS to FB.  Heterogeneity was assessed using I2 and Q statistic.  Publication bias was examined using funnel plots and classic fail-safe test.  A total of 7 studies were included totaling 2,816 patients.  FB identified 158 dysplasia cases, whereas WATS resulted in an additional 114 cases.  The pooled risk ratio (RR) of all dysplasia detection was 1.7 (1.43 to 2.03), p < 0.001, I2 = 0.  For HGD, the pooled RR was 1.88 (1.28 to 2.77), p = 0.001, I2 = 33 %.  The yield of WATS was dependent on the prevalence of dysplasia in the study population.  Among studies with high rates of dysplasia, the absolute increase in dysplasia detection (risk difference, RD) was 13 % (8 % to 18 %, p < 0.0001, number needed to treat [NNT] = 8).  The pooled RD in HGD was 9 % (2 % to 16 %), p < 0.001, NNT = 11.  For studies with a low prevalence of dysplasia, RD for all dysplasia was 2 % (1 % to 3 %), p = 0.001, NNT = 50.  For HGD, the RD was 0.6 % (0.2 % to 1.3 %), p = 0.019, NNT = 166.  The authors concluded that in populations with a high prevalence of dysplasia, adding WATS to FB led to a significant increase in dysplasia detection.  Moreover, these researchers stated that the clinical value of the increased detection rate of dysplasia for WATS needs further investigation because there are limited data regarding how various centers deal with these findings.

The authors stated that they noticed that studies evaluating the use of WATS in BE had several limitations, which included: the variable definition of dysplasia reported crypt dysplasia (CD); indefinite for dysplasia (IND), LGD, and HGD/adenocarcinoma (HGD/AC); varying indications for surveillance and inclusion criteria (surveillance post-EET, surveillance in NDBE); and the fact that most WATS studies were industry-sponsored.  A previous meta-analysis tried to synthesize WATS data but resulted in very high heterogeneity, making the results largely uninterpretable.  This study tried to control for the afore-mentioned limitations in various ways.  The 1st limitation these investigators tried to address was the heterogeneity in dysplasia definition.  Some studies included LGD, while others excluded LGD.  Similarly, some studies included IND with LGD as one category.  Other studies also included CD in the dysplasia categories; thus, trying to analyze all studies together when the outcomes were not the same was inappropriate.  This was a major hurdle in analyzing WATS data and has contributed to the significant heterogeneity reported in a previous meta-analysis with an I2 of 97 %.  Therefore, for the primary analyses, these researchers separated studies based on how dysplasia was reported.  This standardized approach was proposed a priori and was essential for this kind of data synthesis.  The 2nd limitation was the varying indication for surveillance among studies including various inclusion and exclusion criteria.  Most studies included patients undergoing surveillance for BE.  These researchers recognized that the variation in rate of dysplasia in the study population was a major source of heterogeneity.  This was not a factor when calculating relative values; however, it was a major factor when examining absolute effect estimates, i. e., RD.  A study of patients who already had dysplasia and underwent RFA before surveillance would be expected to detect far more cases of dysplasia compared to a study of patients who had mostly NDBE.  The meta-regression indicated that the prevalence of dysplasia was a significant contributor to heterogeneity in calculation of absolute increase in dysplasia detection.  In stratifying the data based on prevalence of dysplasia, these investigators were able to address heterogeneity and calculate more accurate absolute measures and NNT. 

An American Gastroenterological Association (AGA) expert review of on new technology and innovation for surveillance and screening in BE (Muthusamy et al, 2022) included a Best Practice Advice Statement that “[w]ide area transepithelial sampling may be used as an adjunctive technique to sample the suspected or established Barrett’s segment (in addition to the Seattle biopsy protocol)”.  The expert review did not provide a formal rating of the quality of the evidence or strength of the Best Practice Advice Statements.  The expert review stated that “[f]urther prospective studies directly comparing WATS-3D and Seattle protocol are needed to understand if WATS-3D sampling might be as or more effective”.

Guidelines on Barret's esophagus from the American Gastroenterological Association (Shaheen et al, 2022) state that "We could not make a recommendation on the use of wide-area transepithelial sampling with computer-assisted 3-dimensional (WATS-3D) analysis in patients undergoing endoscopic surveillance of BE".

Commenting on American Gastroenterological Association guidelines, Shaheen et al (2022) observed: "WATS3D (CDx Diagnostics, Suffren, NY) is a computer-aided analysis of brush samples which, when used as an adjunct to biopsies, may increase the yield of dysplasia detection while TissueCypher, a tissue systems pathology test, may better prognosticate risk of progression in BE than the traditionally used dysplasia grade. Insufficient evidence exists to allow a general recommendation for the use of either of these technologies, and more work is needed to define the role of adjuncts in risk stratification of BE and LGD". 

van Munster et al (2023) noted that current surveillance for BE, consisting of 4-quadrant random FBs, has an inherent risk of sampling error; WATS may increase detection of HGD and EAC.  In a randomized, multi-center study, these investigators examined the use of WATS as a substitute for FB.  Patients with known BE and a recent history of dysplasia, without visible lesions, at 17 hospitals were randomized to receive either WATS followed by FB or vice versa.  All WATS samples were examined, with computer assistance, by at least 2 experienced pathologists at the CDx Diagnostics laboratory.  Similarly, all FBs were examined by 2 expert pathologists.  The primary endpoint was concordance/discordance for detection of HGD/EAC between the 2 techniques.  A total of 172 patients were included, of whom 21 had HGD/EAC detected by both modalities, 18 had HGD/EAC detected by WATS but missed by FB, and 12 were detected by FB but missed by WATS.  The detection rate of HGD/EAC did not differ between WATS and FB (p = 0.36).  Using WATS as an adjunct to FB significantly increased the detection of HGD/EAC versus FB alone (absolute increase 10 % [95 % CI: 6 % to 16 %]).  Mean procedural times for FB alone, WATS alone, and the combination were 6.6 mins (95 % CI: 5.9 to 7.1), 4.9 mins (95 % CI: 4.1 to 5.4), and 11.2 mins (95 % CI: 10.5 to 14.0), respectively.  The authors concluded that although the combination of WATS and FB increased dysplasia detection in a population of BE patients enriched for dysplasia, these researchers did not find a statistically significant difference between WATS and FB for the detection of HGD/EAC as single modality.  These researchers stated that the hypothesis that WATS would detect 2 times as much dysplasia as FBs; and that the dysplasia detection rate for FBs would be 27 % was too optimistic.  The calculated sample size was however an over-estimation because it was based on independent outcomes.  They noted that WATS as a standalone technique did not detect significantly more HGD or cancer as compared with FBs in an enriched BE population with known dysplasia.

The authors stated that several drawbacks in this study may have biased the detection rates of WATS and/or FB.  First, there is no gold standard for HGD/cancer.  Pathologists who provided the WATS diagnosis derived from a single central laboratory (CDx Diagnostics, Inc.).  This may potentially have led to a different, either lower or higher, threshold for the diagnosis of HGD/EAC than for FB; thus, it was uncertain if a WATS + /FB− HGD diagnosis would represent comparable risk for progression to (advanced) EAC as an FB diagnosis of HGD.  Because most patients in this trial underwent ablation therapy, there was no follow-up data available.  Interestingly, a recent study assessed progression rates to HGD/EAC of an initial WATS diagnosis of either NDBE, crypt dysplasia, or LGD in 4,545 patients who were followed-for a mean of 2 years.  Annual progression rates of 0.1 %, 1.89 %, and 3.47 % were found for baseline NDBE, crypt dysplasia, or LGD, respectively, which were comparable to progression studies carried out with FB (Shaheen et al, 2022).  A new study with long-term endoscopic follow-up for a WATS + /FB− diagnosis of HGD has been initiated to further examine this matter.

Trindade et al (2023) stated that WATS-3D has been shown to increase the diagnostic yield of IM and dysplasia within a segment of suspected or known BE when used as an adjunct to FB; however, few data are available regarding how segment length affects WATS-3D yield.  In a retrospective study, these researchers examined adjunctive WATS-3D use in patients with varying lengths of BE.  A total of 8,471 patients (52.5 % men; mean age of 63 years) enrolled in 2 registry studies were included in this study.  All patients were being screened or surveyed for BE with both FBs as well as WATS-3D.  The adjunctive and absolute yield of WATS-3D was calculated according to the length of the patient's BE segment.  The overall adjunctive and absolute increased diagnostic yields with WATS-3D were 47.6 % and 17.5 %, respectively, for detection of IM, and 139 % and 2.4 % for detection of dysplasia.  IM and dysplasia detection both increased with the use of WATS-3D regardless of segment length.  Increase in IM diagnostic yield was significantly higher in short- versus long-segment cases but higher in long-segment cases for dysplasia detection.  The authors concluded that the findings of this study showed that when WATS-3D was added as an adjunct to FBs, it was effective at increasing the diagnostic yield of both BE and associated dysplasia in patients with both short and long segments of esophageal columnar-lined epithelium.  Moreover, these researchers stated that further prospective studies are needed to determine if WATS-3D can be used potentially as a replacement to FB to detect NDBE and dysplasia in patients with either suspected or known BE, given the known limitations and frequent lack of adherence to the Seattle protocol method of FB tissue sampling in current gastroenterology practice.

The authors stated that this study had several drawbacks.  First, given the study’s retrospective design, some clinical and histologic parameters (e.g., indication for procedure, presence or absence of hiatus hernia/prior dysplasia, adherence to Seattle protocol) were not known for all patients.  However, given the large size of the study cohort (n = 8,471), and the fact that 87 % of patients did have most of these parameters known, a type II statistical error was unlikely.  Second, only a small percentage of patients were found to have dysplasia, which limited the evaluation of added yield of WATS-3D in the BE surveillance group.  Although these patients represented just 3 % of the entire cohort, considering that 39 % of patients were being screened for BE (and therefore at low risk of dysplasia), this value was still higher than expected compared with even a pure surveillance cohort.  Third, information regarding the presence or absence of focal raised lesions was unavailable in any of the patients.  As such, it was not possible to determine what proportion of FBs were “targeted” versus truly “non-targeted” (as outlined in the Seattle protocol).  WATS-3D is not clinically indicated for targeted sampling of focal lesions; thus, sampling of focal lesions may have led to a selection bias in favor of FB over WATS-3D for dysplasia detection.  Fourth, as mentioned earlier, data on the frequency of adherence to Seattle protocol biopsies were unavailable.  However, enrollment in the associated registries stipulated that the Seattle protocol should be used for FB sampling.  Fifth, there was no central pathology review or an ability to determine what proportion of FBs were reviewed by a 2nd expert BE pathologist; therefore, a head-to-head comparison of FBs and WATS-3D specimens was unable to be conducted.  In contrast, all WATS-3D dysplasia diagnoses were confirmed by a 2nd pathologist.

DNA-Image Cytometry of Brush Biopsies

Siebers and colleagues (2013) stated that despite advances in surgical and other treatment modalities, the prognosis of patients with OSCC remains poor.  It is well-known that the early detection of OSCC and recurrent lesions is of utmost importance in obtaining disease control.  Besides difficulty in visually differentiating between benign and (pre) cancerous lesions, the detection is hampered by the fact that scalpel biopsy is an invasive activity with potential morbidity.  It is therefore not recommended to biopsy lesions on a regular basis.  An easily performed, non-invasive screening method suitable to monitor lesions over time is urgently needed.  In addition, the current histopathological examination suffers from inter- and intra-observer variability.  In a previous study these researchers showed the prognostic value of DNA image cytometry (DNA-ICM).  The objective of the present study is assessment of the possibility to determine ploidy status using an oral brush.  This prospective study included 85 (23 pre-malignancies, 27 stage T1 and 31 stage T2 OSCC) patients with a suspected (pre) malignant lesion of the oral cavity.  Newly discovered lesions as well as suspected recurrent OSCC were included.  Both a brush and biopsy specimen were obtained for each patient.  All specimens were analyzed using ICM according to a well-established procedure.  A significant difference was observed between brushes from diploid biopsies and brushes from non-diploid biopsies (p < 0.01).  The brush was able to significantly differentiate between diploid and non-diploid lesions.  This technique was able to correctly identify 50 % of the non-diploid lesions with a corresponding specificity of 80 %.  The authors concluded that the oral brush biopsy is not suitable to replace the conventional surgical biopsy, however it may be of additional value in monitoring (pre) malignant lesions over time.

Kammerer et al (2013) stated that adjunctive techniques like DNA-ICM, a non-invasive method, have been attributed to enhance the diagnostic performance of oral brush biopsies.  The aim of the study was an evaluation of brush biopsies, analyzed according to morphological criteria and by DNA-ICM versus histological findings in a blinded prospective trial.  A total of 88 brush biopsies of 70 patients were sampled.  Only clinical suspicious but not evident malignant oral lesions were included.  Clinical diagnosis was leukoplakia (n = 36), lichen planus (n = 18), verruciform erythroplakia (n = 12), erythroleukoplakia (n = 9), erosion (n = 7) and induration (n = 6).  Evaluation was conducted via histology, cytology and DNA-ICM.  Histological diagnosis revealed 8 cases of squamous intraepithelial dysplasia (SIN 1 n = 6, SIN 2 n = 2), 4 cases of carcinoma-in situ and 25 cases of oral T1-cancer.  Remaining cases were leukoplakia (n = 28), lichen planus (n = 15) and local inflammation (n = 8).  Brush biopsy detected malignant lesions including SIN 1 with a sensitivity of 55 % and a specificity of 100 %.  DNA-ICM had a sensitivity of 70 % and a specificity of 100 %.  The combination of both methods showed a sensitivity of 76 % and a specificity of 100 %.  The predominant reason for false negative results was sampling errors with insufficient cells (86 % in brush biopsy and 100 % in DNA-ICM).  The authors concluded that DNA-ICM has the potential to substantially improve the sensitivity of a pure morphological interpretation of oral brush biopsies.  Method inherent sampling errors may be accountable for a lower sensitivity compared to conventional histological diagnosis.  Therefore, DNA-ICM should not be used to rule out malignancy, when lesions are already clinically suspicious for oral cancer.

Ma and colleagues (2014) estimated the diagnostic accuracy of brush biopsy with DNA-ICM for potentially malignant oral disorders compared with tissue biopsy pathology in China.  Exfoliative cells were obtained using a cytobrush cell collector from oral mucosa of 52 subjects, followed by scalpel biopsy from the same region.  Nuclear DNA contents (ploidy) were measured after Feulgen re-staining, using an automated DNA image cytometer.  Exfoliative cytology with DNA-ICM and histopathological diagnosis were performed separately at different institutions.  Histological investigation was considered the gold standard.  These researchers reported that the sensitivity of DNA aneuploidy for the detection of cancer cells in potentially malignant oral disorders was 86.36 %; its specificity was 90.00 %, its PPV was 86.36 %, and its NPV was 90.00 %.  The authors concluded that brush biopsy with DNA-ICM is a useful method for monitoring potentially malignant oral disorders.  The findings of this small, uncontrolled study need to be validated by well-designed studies.

The U.S. Preventive Services Task Force (USPSTF)’s guideline on “Screening for oral cancer” (USPSTF, 2014) stated that “Additional tests proposed as adjuncts to the oral cancer screening examination include toluidine blue dye staining, chemiluminescent and autofluorescent lighting devices, and brush cytopathology.  These screening and adjunct tests have not been adequately tested in primary care non dental settings.  Although there is interest in screening for oral HPV infection, medical and dental organizations do not recommend it.  Currently, no screening test for oral HPV infection has been approved by the U.S. Food and Drug Administration (FDA)”.

Ye and colleagues (2015) conducted a metaanalysis to compare the accuracy between the OralCDx brush biopsy and DNA-image cytometry in diagnosing both conditions.  The authors systematically searched bibliographic databases for original relevant studies on the early diagnosis of oral precancer and oral cancer.  They evaluated study characteristics to determine the accuracy of the 2 screening strategies.  They identified 13 studies (8 of OralCDx brush biopsy and 5 of DNA-image cytometry) reporting on 1,981 oral mucosa lesions.  The meta-analysis found that the area under the summary receiver operating characteristic curves of the OralCDx brush biopsy and DNA-image cytometry were 0.8879 and 0.9885, respectively.  The pooled sensitivity, specificity, and diagnostic odds ratio (OR) of the OralCDx brush biopsy were 86 % (95 % CI: 81 to 90), 81 % (95 % CI: 78 to 85), and 20.36 (95 % CI: 2.72 to 152.67), respectively, while these modalities of DNA-image cytometry were 89 % (95 % CI: 83 to 94), 99 % (95 % CI: 97 to 100), and 446.08 (95 % CI: 73.36 to 2712.43), respectively.  Results of a pairwise comparison between each modality demonstrated that specificity, area under the curve (AUC), and Q(∗) index of DNA-image cytometry was significantly higher than that of the OralCDx brush biopsy (Z = 2.821, p < 0.05; Z = 1.711, p < 0.05; Z = 1.727, p < 0.05), but no significant difference in sensitivity was found (Z = 1.520, p > 0.05).  The authors concluded that the metaanalysis of the published studies indicated that DNA-image cytometry is more accurate than the OralCDx brush biopsy in diagnosing oral precancer and oral cancer.

In a meta-analysis, Abt (2015) examined the clinical value of DNA-image cytometry for detecting oral cancer.  Medline, Embase, PubMed, Elsevier and Web of Science databases and the reference lists of known primary and review papers were scanned for relevant citations.  Prospective and retrospective studies evaluating brush cytology were considered.  Only computer-assisted methods that included histologically confirmed disease positive status were included.  Data were extracted using a standardized form.  Study quality was assessed by 1 reviewer using the quality assessment of diagnostic accuracy studies (QUADAS) checklist.  Pooled sensitivity and specificity were calculated with 95 % CIs separately for each study.  Likelihood and diagnostic odds ratios were also calculated along with a summary receiver-operating characteristic (SROC) curve analysis.  A total of 13 studies (8 of OralCDx brush biopsy and 5 of DNA-image cytometry) reporting on 1,981 oral mucosa lesions were included.  OralCDx brush biopsy had a pooled sensitivity of 86 % (95 % CI: 81 to 90) and pooled specificity of 81 % (95 % CI: 78 to 85).  The pooled sensitivity and specificity of DNA-image cytometry were 89 % (95 % CI: 83 to 94) and 99 % (95 % CI: 97 to 100).  Diagnostic OR estimates for OralCDx brush biopsy and DNA-image cytometry were 20.36 (95 % CI: 2.72 to 152.67) and 446.08 (95 % CI: 73.36 to 2712.43), respectively.  Study size was found to be closely related to heterogeneity among studies and analysis suggested publication bias in relation to OralCDx brush biopsy.  The authors concluded that these findings suggested that DNA-image cytometry had a highly significant potential over OralCDx brush biopsy as an accurate and simple diagnostic tool for clinically suspected oral pre-cancer and oral cancer.

RNA-Based Oral Brush Biopsy for the Detection and Prognosis of Oral Malignancy

Adami and colleagues (2017) stated that RNA-based diagnosis and prognosis of SCC has been slow to come to the clinic.  Improvements in RNA measurement, statistical evaluation, and sample preservation, along with increased sample numbers, have not made these methods reproducible enough to be used clinically.  These researchers proposed that, in the case of OSCC, a chief source of variability is sample dissection, which leads to variable amounts of stroma mixed in with tumor epithelium.  This heterogeneity of the samples, which requires great care to avoid, makes it difficult to see changes in RNA levels specific to tumor cells.  An evaluation of the data suggested that, paradoxically, brush biopsy samples of oral lesions may provide a more reproducible method than surgical acquisition of samples for microRNA (miRNA) measurement.  The evidence also indicated that body fluid samples can show similar changes in miRNAs with OSCC as those seen in tumor brush biopsy samples, suggesting much of the miRNA in these samples is coming from the same source -- tumor epithelium.  The authors concluded that brush biopsy or body fluid samples may be superior to surgical samples in allowing miRNA-based diagnosis and prognosis of OSCC in that they feature a rapid method to obtain homogeneous tumor cells and/or RNA.

Zhang and co-workers (2017) noted that OSCC is one of the most malignant tumors with high mortality rate worldwide.  Biomarker discovery is critical for early diagnosis and precision treatment of this disease.  MicroRNAs are small non-coding RNA molecules, which often regulate essential biological processes and are good candidates for biomarkers.  By integrative analysis of both the cancer-associated gene expression data and microRNA-mRNA network, miR-148b-3p, miR-629-3p, miR-27a-3p, and miR-142-3p were screened as novel diagnostic biomarkers for OSCC based on their unique regulatory abilities in the network structure of the conditional microRNA-mRNA network and their important functions.  These researchers identified 5 microRNAs that could be putative biomarkers for OSCC.  Among them, 1 has been reported as biomarker and 2 are reported as associated microRNAs.  The other 2 are the novel finding microRNA biomarkers.  As a result, 4 novel biomarker microRNAs (i.e., miR-148b-3p, miR-629-3p, miR-27a-3p, and miR-142-3p) are discovered.  The authors concluded that further experimental verification and clinical testing were suggested for these putative OSCC microRNA biomarkers.

Yan and colleagues (2017) stated that several studies have been shown that miRNA play important roles during the progression of OSCC.  However, the results varied largely in different studies due to different platforms and sample sizes.  These investigators systematically evaluated a large scale of miRNA profiles from current qualified OSCC samples, and further examined the functions of genes regulated by these key miRNAs as well as the signaling pathways through which these miRNA effect carcinogenesis.  A total of 7 key miRNAs were identified, and of which 3 were significantly up-regulated, including hsa-miR-21, hsa-miR-31, hsa-miR-338, and 4 were down-regulated, namely hsa-miR-125b, hsa-miR-133a, hsa-miR-133b, and hsa-miR-139.  The function enrichment analysis revealed that target genes of up-regulated miRNAs were associated with cellular protein metabolic process, macromolecule metabolic process, and TGF-beta pathway, while the targets of down-regulated miRNAs were enriched in negative regulation of macromolecule biosynthetic process and gene expression, and p53, long-term potentiation and adherens junction pathways.  Transcription factor analysis revealed that there were 67 (51.1 %) transcription factors influenced by both up- and down-regulated miRNAs.  The authors concluded that 7 key miRNAs were found to play essential role in progression of OSCC, as well as the target genes and transcription factors of these miRNAs.  They stated that the potential functions of these target genes identified in this study may be useful in the diagnosis and prognostic prediction of OSCC as biomarkers.

In a systematic review, El-Sakka and associates (2018) evaluated current findings on altered expression of miRNAs in OPMDs and whether they can be used as risk stratification biomarkers.  Studies were collated after searching 3 different electronic databases: PubMed, Embase, Medline.  Additional searches were carried out through cross-checking the bibliographies of selected articles.  After a thorough selection process made by 2 of the authors, 40 articles met the inclusion criteria and were included in the review.  Studies were assessed and analyzed in terms of how the candidate miRNA biomarkers were differentially expressed and validated.  The included studies examined the expression of miRNAs from human specimens (blood serum/plasma, saliva, tissue) as diagnostic or prognostic biomarkers in patients with OPMDs, some of which have been utilized as risk stratification biomarkers for malignant transformation and have showed promising findings.  The authors concluded that the current evidence to support or refute the prognostic utility of miRNAs in predicting cancer progression in OPMDs is equivocal.  They stated that further well-designed longitudinal prospective studies are needed.

Furthermore, an UpToDate review on “Overview of the diagnosis and staging of head and neck cancer” (Poon and Stenson, 2018) does not mention RNA-based methods as a diagnostic tool.

Esophageal Balloon for Circumferential Cytologic Sampling

Kohli et al (2021) noted that a previous publication introduced the Strome-Blitzer balloon's ability to obtain circumferential esophageal cytologic sampling.  This GLP study was requisite for FDA approval to determine if equivalent cell capture and cellularity was observed with the balloon compared to surface sampling brushes and to determine the balloon's usability for naive otolaryngologists.  A total of 3 naive users tested the Hobbs brush and Strome-Blitzer balloon on 4 Yorkshire swine; 4 anatomical sites were sampled, beginning distally and ending proximally.  In 2 animals, the balloon was used first distally and in the remaining 2, 4 new Hobbs brushes were used distally first.  Moving proximally, the balloon and brushes were sequentially alternated.  In follow-the-leader fashion, the balloon was introduced trans-orally followed by an endoscope to the desired site.  The balloon was inflated exposing the abrasive strips to contact the esophageal mucosa.  Moving the balloon 1 to 2 cm superiorly and inferiorly effected circumferential cell capture.  The balloon was collapsed and removed, preserving the cellularity.  The Hobbs brush was passed through the scope's channel.  Four brushes, 1 per quadrant, obtained the samples at an anatomical site.  The balloon was rated as pass/fail on the following: delivery, kinking, usability, and malfunction.  A blinded veterinary pathologist evaluated the cytology.  There was no device malfunction, mucosal trauma, or difficulty with device use.  Balloon cytologic samples were comparable in cellularity and quality to the brush.  The authors concluded that a single balloon sampling was comparable to 4 brushes in capturing diagnostically relevant cellular volumes and architecture.  Naive users easily performed the procedures after reading the guidelines.  Level of Evidence = III.


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