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Background
The usual method for delivering radiation is external beam with high-energy photons. However, the external beam doses required to achieve local tumor control can exceed the radiation tolerance of some normal organs and other structures of the body.
Intra-operative radiation therapy (IORT) is being investigated as a technique to deliver a high dose of radiation to a locally advanced tumor while attempting to protect adjacent normal tissues at the time of surgery. It is delivered with applicators and cones attached to the treatment head of high-energy medical linear accelerators. After all or most of the cancer is surgically removed, a large, single-dose of high-energy radiation is aimed directly at the tumor site. Nearby healthy tissue is protected with special shields.
The goal of IORT is to enhance local tumor control. Most patients receiving IORT are concurrently treated with high-dose external beam photon irradiation. The term “intraoperative radiation therapy” may also refer to intra-operative brachytherapy, the temporary or permanent implantation of radioactive seeds.
Intra-operative radiation therapy is usually a component of a multi-disciplinary treatment approach for localized cancers that can not be completely removed or that have a high risk of recurring in nearby tissues. For patients with colorectal cancer, IORT has been associated with improved local control. Several case series have demonstrated that adjuvant IORT has the potential to improve response rates with acceptable toxicities and improve survival with locally advanced colorectal cancer (Taylor et al, 2002; Ratto et al, 2003; Hashiguchi et al, 2003; Pacelli et al, 2004). Thus, the positive impact of IORT on local control of colorectal cancer appears to justify the inclusion of this therapeutic modality.
Pacelli et al (2004) reported early and long-term results of pre-operative radiotherapy plus IORT to total mesorectal excision of middle and lower T3 rectal cancer patients (n = 113). Five-year, disease-specific survival was 81.4 % for those patients receiving pre-operative radiotherapy plus IORT (n = 69) compared to 58.1 % for those patients in the mesorectal excision group (n = 44). The rates of local recurrence at 5 years were 6.6 % and 23.2 % in pre-operative radiotherapy plus IORT group and total mesorectal excision group, respectively. The authors concluded that pre-operative radiotherapy plus IORT associated with total mesorectal excision reduced local recurrence rate and improved survival in T3 rectal cancer compared with total mesorectal excision alone.
Persons from the American Society of Therapeutic Radiation and Oncology (ASTRO) have commented that “[c]urrently, it [IORT] is primarily used for treating rectal cancers, although in the near future it may be used for additional sites. Studies indicate that IORT might be used to treat head and neck, abdomen, and pelvic cancers, and cancers in the extremities. IORT can reduce the length of treatment. The Stanford Cancer Center states, 'In some cases, no further radiation treatment is required following IORT making it a much more convenient approach for delivering therapy. Furthermore, physicians are able to shield surrounding organs from radiation, limiting side effects to healthy tissue" (Demanes and Rieke, 2005).
The National Comprehensive Cancer Network (NCCN) Clinical Practice Guidelines for Oncology recommends IORT for colorectal cancers and uterine cancers. Regarding the use of IORT in colon cancer, NCCN guidelines state: “Intraoperative radiation therapy, if available, should be considered for patients with T4 or recurrent cancers as an additional boost. Preoperative radiation is preferred for these patients to aid resectability. If IORT is not available, low dose external beam radiation could be considered, prior to adjuvant chemotherapy” (NCCN, 2006).
NCCN guidelines also recommend the use of IORT in selected rectal cancers: “Intraoperative radiation therapy, if available, should be considered for very close or positive margins after resection, as an additional boost especially for patients with T4 or recurrent cancers. If IORT is not available, 10 to 20 Gy external beam radiation to a limited volume could be considered soon after surgery, prior to adjuvant chemotherapy" (NCCN, 2006).
Regarding the use of IORT for uterine cancers, NCCN guidelines state that: “For patients previously treated with external-beam RT, recommended salvage therapy includes pelvic exenteration with or without IORT, palliative radiotherapy, hormonal therapy, or chemotherapy. Radical surgery, such as pelvic exenteration, has been performed with reported survival rates approximating 20 %. For patients without prior RT to the site of recurrence, or with previous brachytherapy only, surgical exploration of pelvis and abdomen should be performed with or without IORT” (NCCN, 2005).
NCCN guidelines also discuss the use of IORT in cervical cancers: “Patients with a localized recurrence of cervical cancer after surgery should be evaluated for salvage radiotherapy. Salvage rates of approximately 40 % have been reported in such situations. For patients who experience pelvic recurrences with no prior radiation therapy or who experience recurrences outside of the previously treated field, salvage therapy includes definitive pelvic radiation with or without platinum-based chemotherapy with or without brachytherapy. Patients with central pelvic recurrent disease after radiation therapy should be evaluated for pelvic exenteration, with or without IORT (or, in carefully selected patients with small lesions, radical hysterectomy or interstitial reirradiation). Surgical mortality is generally 5 % or lower, with survival rates between 20 % and 6 %. Concomitant measures with such radical procedures include adequate rehabilitation programs dealing with the psychosocial and psychosexual consequences of the operation and reconstructive procedures. Recurrence after pelvic exenteration should be treated with platinum-based chemotherapy or best supportive care or be enrolled in a clinical trial. Those with non-central disease should be treated with pelvic exenteration/laterally extended endopelvic resection/IORT, platinum-based chemotherapy, best supportive care, or participation in a clinical trial” (NCCN, 2005).
A review of IORT in the management of locally advanced gynecological malignancies by del Carmen et al (2000) reported that IORT can be utilized to maximize local tumor control. According to del Carmen and colleagues, “[r]eview of the available literature indicates that IORT may improve long-term local control and overall survival in women with pelvic sidewall and/or para-aortic nodal recurrence. The most encouraging results have been reported in cases with microscopic residual disease, following surgical debulking.” According to a more recent review by del Carmen and colleagues (2003), “[h]igher 5-year disease-free and overall survival rates have been documented in women who have microscopic residual disease, compared with those who have gross residual disease.”
Orecchia et al (2006) stated that IORT has been used in the treatment of various malignancies, mostly in combination with external beam radiation therapy. The long-term results suggest a positive impact on local controls that appear to be associated with increased survival. Modern IORT can be performed either with electron beams or photons, and has been used recently in early-stage cancer as a boost or as an exclusive treatment, especially for breast tumors, with extremely promising results. The results of different clinical studies have shown the feasibility of the technique and it is expected that its application will become more widespread in the immediate future. The authors noted that intraoperative electron radiotherapy in the treatment of initial-stage breast cancer may be an excellent alternative to external beam radiation therapy in an appropriate selected group of patients; however, intensive long-term follow-up is needed to better assess local control and possible side effects.
Sauer and colleagues (2007) stated that breast-conserving surgery followed by whole-breast radiotherapy (WBRT) has become the standard treatment for the majority of patients with early breast cancer. While the indications for systemic adjuvant treatment have continuously expanded, there is a tendency to restrict post-operative radiotherapy to accelerated partial breast irradiation (APBI) instead of WBRT. These investigators described various techniques of APBI; and their respective advantages or potential drawbacks. Moreover, they reviewed the scientific evidence in the literature, which forms the basis for the consensus statements and recommendations of the German Society of Radiation Oncology, the German Society of Senology, and the Working Group for Gynecological Oncology of the German Cancer Society. The methods mainly used for APBI are: interstitial radiotherapy with multi-catheter technique, IORT, the MammoSite, or 3-D conformal external beam radiotherapy. These techniques have marked differences in dose distribution and homogeneity. The published range of local recurrence rates varies between 0 % to 37 %, the median follow-up from 8 to 72 months. The authors concluded that to-date, follow-up times mostly do not yet permit a definite judgment concerning the long-term effectiveness and side effects of APBI. The relevant societies in Germany support randomized clinical studies comparing APBI with WBRT in a well-defined subset of low-risk patients. Moreover, the authors expressly discouraged the routine use of APBI outside clinical trials. Until definite results show that APBI neither impairs therapeutic outcome nor cosmetic results, WBRT remains the gold standard in the treatment of early breast cancer.
The conclusion by Sauer et al (2007) is in agreement with that of Mitsumori and Hiraoka (2008) who noted that APBI is still an investigational treatment in Japan, and the optimal method of radiation delivery as well as its long-term safety and effectiveness should be ascertained in clinical trials. In this regard, Blohmer et al (2008) stated that ongoing prospective and randomized studies are investigating for which patients IORT is sufficient as the sole irradiation method after previous surgery.
Kalapurakal et al (2006) reported the findings of a phase I study in which IORT (first dose level of 10 Gy) with the photon radiosurgery system was used to treat children with recurrent brain tumors. A total of 14 children received IORT; 8 had been previously irradiated. Thirteen children had ependymoma. The median follow-up period was 16 months. Three patients (21 %) developed radiation necrosis on follow-up MRI scans 6 to 12 months after IORT. They had not been previously irradiated and had received 10 Gy to a depth of 5 mm. One required surgery and the other 2 had resolution of their lesions without treatment. All 3 patients were asymptomatic at the last follow-up. No other late toxicity was observed at the last follow-up visit. Eight patients (57 %) had tumor control within the surgical bed after IORT. The authors concluded that these findings demonstrated the safety and feasibility of IORT to a dose of 10 Gy to 2 mm in children with previously irradiated brain tumors, while IORT to a dose of 10 Gy at 5 mm was associated with a greater complication rate.
Bergenfeldt and Albertsson (2006) summarized the development of adjuvant therapy for pancreatic cancer over the last 20 years. Four randomized controlled trials compared long-term survival of different treatments. The small GITSG-study supported combined chemoradiation, but the EORTC-study found no significant effect. A Norwegian study of adjuvant chemotherapy found an increased median survival, but no effect beyond 2 years. The large ESPAC-1 study showed a benefit for 5-FU based chemotherapy, while chemoradiation had a negative effect. Thus, evidence favors adjuvant therapy, but 5-FU may not be the ultimate drug. Support for gemcitabine is given by preliminary data from a German randomized trial, and further American and European studies are upcoming. However, post-operative therapy is problematic, as 20 to 30 % of resected patients never undergo treatment because of slow recovery or other reasons. Pre-operative therapy has some theoretical advantages, and moreover, patients with rapidly progressive disease may be spared surgery. Randomized controlled trials are lacking, but published results compared well with post-operative, adjuvant therapy. The value of locally targeted therapy is difficult to assess. Reasonable results have been obtained with regional chemotherapy, whereas IORT does not seem to increase survival despite reducing local recurrences.
Ruano-Ravina et al (2008) evaluated the safety and effectiveness of IORT in pancreatic cancer. These investigators conducted a systematic review of scientific literature from January 1995 to February 2007, including Medline, Embase, ISI Web of Science and HTA (Health Technology Assessment). By applying a series of inclusion criteria, 2 independent reviewers selected those studies in which a minimum of 30 patients received IORT and which furnished survival results based on a minimum 3-month follow-up. A total of 14 papers were included, 1 was an IORT assessment report, 5 were cohort studies, and the remaining 8 were case series studies, 2 of which belonged to the same series. In general, these studies showed that IORT could slightly increase survival among patients with pancreatic cancer in localized stages. However, the results were not conclusively in favor of IORT in the case of pancreatic cancer in locally advanced and metastatic stages. There were no published studies that assessed quality of life. The authors concluded that there is no clear evidence to indicate that IORT is more effective than other therapies in treating pancreatic cancer in locally advanced and metastatic stages.
Showalter et al (2009) performed a retrospective analysis of patients who underwent pancreatico-duodenectomy (PD) between 1995 and 2005 to identify patients who underwent resection with and without IORT. Data collected included age, gender, complications, margin status, stage, survival, and recurrence. Unadjusted analyses of the IORT and non-IORT groups were performed using Fisher's chi-square method for discrete variables and Wilcoxon rank sum test for continuous variables. To account for biases in patient selection for IORT, a propensity score was calculated for each patient and adjusted statistical analyses were performed for survival and recurrence outcomes. Between January 1995 and November 2005, a total of 122 patients underwent PD for peri-ampullary tumors, including 99 pancreatic cancers. Of this group, 37 patients were treated with IORT, and there was adequate follow-up information for a group of 46 patients who underwent PD without IORT. The IORT group contained a higher percentage of Stage IIB or higher tumors (65 %) than in the non-IORT group (39.1 %), though differences in stage did not reach significance (p = 0.16). There was a non-significant decrease in the rate of loco-regional recurrence in patients who had IORT (39 % non-IORT versus 23 % IORT, p = 0.19). The median survival time of patients who received IORT was 19.2 months, which was not significantly different than patients managed without IORT, 21.0 months (p = 0.78). In the propensity analyses, IORT did not significantly influence survival or recurrence after PD. The authors concluded that IORT can be safely added to management approaches for resectable pancreatic cancer, with acceptable morbidity and mortality. However, IORT did not improve loco-regional control and did not alter survival for patients with resected pancreatic cancer. In the future, IORT may be combined with novel therapeutic agents in the setting of a clinical trial in order to attempt to improve outcomes for patients with pancreatic cancer.
Czito and colleagues (2006) stated that the prognosis of patients with biliary cancers is poor. Although surgery is potentially curative in selected patients, local recurrence is common. The use of adjuvant or neoadjuvant radiation therapy improves local control and possibly survival. In locally advanced patients, radiation therapy provides palliation and may prolong survival. Concurrently administered chemotherapy may further enhance these results. Newer radiation therapy techniques, including intra-luminal transcatheter brachytherapy, IORT, intensity-modulated radiation therapy (IMRT), and 3- and 4-dimensional treatment planning, permit radiation dose escalation without significant increases in normal tissue toxicity, thus increasing the effective radiation dose. Preliminary results of studies employing hepatic transplantation with radiation therapy are encouraging. Although these new approaches hold promise, the prognosis in patients with biliary cancers remains poor, and the integration of novel therapeutic strategies is indicated.
Tzeng et al (2006) noted that retroperitoneal soft-tissue sarcoma is an uncommon cancer that is difficult to treat because of its location and proximity to vital organs. Complete gross resection, often involving en bloc resection, is the standard of care as it represents the only treatment that improves overall survival. Unlike extremity sarcoma, retroperitoneal sarcoma tumor mortality is from local recurrence. Radiation therapy is the only adjuvant treatment that has improved local control in several institutional series. However, there remains no definitive prospective, randomized controlled study that establishes the role of adjuvant radiation versus no radiation. Owing to significant radiation morbidity with adjacent organs, especially the small intestine, there exists no consensus on radiation timing, delivery method or dosing. Recent and current protocols use pre-operative external-beam radiation with or without a method of focal boost dosing. Methods of boost dosing include brachytherapy, IORT and IMRT. Further studies are needed to definitively include radiation therapy in the standard treatment of retroperitoneal soft-tissue sarcoma and to find the optimal balance between acceptable radiation toxicity and effective local control in treatment protocols.
Ballo and colleagues (2007) assessed the clinical outcomes of patients with localized retroperitoneal soft tissue sarcoma (STS) treated with complete surgical resection and radiation. The medical records of 83 patients were reviewed retrospectively; 60 patients presented with primary disease and the remaining 23 had recurrence after previous surgical resection. With a median follow-up of 47 months, the actuarial overall disease-specific survival (DSS), distant metastasis-free survival, and local control (LC) rates were 44 %, 67 %, and 40 %, respectively. Of the 38 patients dying of disease, local disease progression was the sole site of recurrence for 16 patients and was a component of progression for another 11 patients. Multi-variate analysis indicated that histological grade was associated with the 5-year rates of DSS (low-grade, 92 %; intermediate-grade, 51 %; and high-grade, 41 %, p = 0.006). Multi-variate analysis also indicated an inferior 5-year LC rate for patients presenting with recurrent disease, positive or uncertain resection margins, and age greater than 65 years. The data did not suggest an improved local control with higher doses of external-beam radiation (EBRT) or with the specific use of IORT. Radiation-related complications (10 % at 5 years) developed in 5 patients; all had received their EBRT post-operatively. The authors concluded that although pre-operative radiation therapy and aggressive surgical resection is well-tolerated in patients, local disease progression continues to be a significant component of disease death. In this small cohort of patients, the use of higher doses of EBRT or IORT did not result in clinically apparent improvements in outcomes.
Patel and DeLaney (2008) noted that bone sarcomas are rare primary tumors. Radiation therapy (RT) can be useful in securing local control in cases where negative surgical margins can not be obtained or where tumors are not resected. Recent technical advances in RT offer the opportunity to deliver radiation to these tumors with higher precision, thus allowing higher doses to the tumor target with lower doses to critical normal tissues, which can improve local tumor control and/or reduce treatment-related morbidity. These researchers conducted a survey of recent technical developments that have been applied to RT for bone sarcomas. Radiation therapy techniques that show promise include intensity-modulated photon RT, 3-D conformal proton RT, intensity-modulated proton RT, heavy charged-particle RT, IORT, and brachytherapy. All of these techniques permit the delivery of higher radiation doses to the target and less dose to normal tissue than had been possible with conventional 3-D conformal radiation techniques. Protons deliver substantially less dose to normal tissues than photons. The authors concluded that data from clinical studies using these advanced radiation techniques suggest that they can improve the therapeutic ratio (the ratio of local control efficacy to the risk of complications).
In a feasibility study, Marucci et al (2008) evaluated the acute toxicity of IORT delivered as an "early boost" after tumor resection in patients with locally advanced head and neck cancer. A total of 25 patients were enrolled in the study. All patients underwent surgery with radical intent, and 17 had microvascular flap reconstruction. The IORT was delivered in the operating room; 20 patients received adjuvant EBRT. Five patients experienced various degrees of complications in the post-operative period, all of which were treated conservatively. One patient had a partial flap necrosis after EBRT that was treated with flap removal. Six deaths were recorded during the mean follow-up period of 8 months; none of the deaths was related to radiation treatment. The authors concluded that these findings showed that the use of IORT as an early boost is feasible with no increase in acute toxicity directly attributable to radiation.
Perry et al (2010) reported the use of high-dose-rate IORT (HDR-IORT) for recurrent head-and-neck cancer (HNC) at a single institution. A total of 34 subjects with recurrent HNC received 38 HDR-IORT treatments using a Harrison-Anderson-Mick applicator with Iridium-192. A single fraction (median of 15 Gy; range of 10 to 20 Gy) was delivered intra-operatively after surgical resection to the region considered at risk for close or positive margins. In all patients, the target region was previously treated with EBRT (median dose of 63 Gy; range of 24 to 74 Gy). The 1- and 2-year estimates for in-field local progression-free survival (LPFS), loco-regional PFS (LRPFS), distant metastases-free survival (DMFS), and overall survival (OS) were calculated. With a median follow-up for surviving patients of 23 months (range of 6 to 54 months), 8 patients (24 %) are alive and without evidence of disease. The 1- and 2-year LPFS rates are 66 % and 56 %, respectively, with 13 (34 %) in-field recurrences. The 1- and 2-year DMFS rates are 81 % and 62 %, respectively, with 10 patients (29 %) developing distant failure. The 1- and 2-year OS rates are 73 % and 55 %, respectively, with a median time to OS of 24 months. Severe complications included cellulitis (n = 5), fistula or wound complications (n = 3), osteo-radionecrosis (n = 1), and radiation-induced trigeminal neuralgia (n = 1). The authors concluded that HDR-IORT has shown encouraging local control outcomes in patients with recurrent HNC with acceptable rates of treatment-related morbidity. They stated that longer follow-up with a larger cohort of patients is needed to fully assess the benefit of this procedure.
Drognitz et al (2008) retrospectively analyzed the impact of IORT on long-term survival in patients with resectable gastric cancer. From 1991 to 2001, a total of 84 patients with gastric neoplasms underwent gastectomy or subtotal resection with IORT (23 Gy, 6 to 15 MeV; IORT-positive [IORT(+)] group). Patients with a history of additional neoadjuvant chemotherapy, histologically confirmed R1 or R2 resection, or reoperation with curative intention after local recurrence were excluded from further analysis. The remaining 61 patients were retrospectively matched with 61 patients without IORT (IORT-negative [IORT(-)] group) for Union Internationale Contre le Cancer (UICC) stage, patient age, histologic grading, extent of surgery, and level of lymph node dissection. Subgroups included post-operative UICC stages I (n = 31), II (n = 11), III (n = 14), and IV (n = 5). Mean follow-up was 4.8 years in the IORT(+) group and 5.0 years in the IORT(-) group. The overall 5-year patient survival rate was 58 % in the IORT(+) group versus 59 % in the IORT(-) group (p = 0.99). Subgroup analysis showed no impact of IORT on 5-year patient survival for those with UICC stages I/II (76 % versus 80 %; p = 0.87) and III/IV (21 % versus 14 %, IORT(+) versus IORT(-) group; p = 0.30). Peri-operative mortality rates were 4.9 % and 4.9 % in the IORT(+) versus IORT(-) group. Total surgical complications were more common in the IORT(+) than IORT(-) group (44.3 % versus 19.7 %; p < 0.05). The loco-regional tumor recurrence rate was 9.8 % in the IORT(+) group. The authors concluded that use of IORT was associated with low loco-regional tumor recurrence, but had no benefit on long-term survival while significantly increasing surgical morbidity in patients with curable gastric cancer.
In a phase I-II study, Saracino et al (2008) examined the use of IORT following radical prostatectomy for prostate cancer. A total of 34 patients with localized prostate cancer with only 1 risk factor (Gleason score greater than or equal to 7, Clinical Stage [cT] greater than or equal to 2c, or prostate-specific antigen [PSA] of 11 to 20 ng/ml) and without clinical evidence of lymph node metastases were treated with radical prostatectomy (RP) and IORT on the tumor bed. A dose-finding procedure based on the Fibonacci method was employed. Dose levels of 16, 18, and 20 Gy were selected, which are biologically equivalent to total doses of about 60 to 80 Gy administered with conventional fractionation, using an alpha/beta ratio value of 3. At a median follow-up of 41 months, 24 (71 %) patients were alive with an undetectable PSA value. No patients died from disease, whereas 2 patients died from other malignancies. Loco-regional failures were detected in 3 (9 %) patients, 2 in the prostate bed and 1 in the common iliac node chain outside the radiation field. A PSA rise without local or distant disease was observed in 7 (21 %) cases. The overall 3-year biochemical progression-free survival rate was 77.3 %. The authors concluded that this dose-finding study showed the feasibility of IORT in prostate cancer also at the highest administered dose.
In a phase II clinical study, Lemanski et al (2010) examined the feasibility and the effectiveness of IORT as an alternative to conventional boost radiation after breast-conserving surgery in elderly patients. These investigators included 94 patients older than 65 years. Among them, 42 patients presented with all the inclusion criteria, i.e., stages pT0 to pT1 and pN0, ductal invasive unifocal carcinoma, and tumor-free margin of greater than 2 mm. Intra-operative radiation therapy was delivered using a dedicated linear accelerator. One 21-Gy fraction was prescribed and specified at the 90 % isodose, using electrons. In-vivo dosimetry was performed for all patients. The primary end point was the quality index. Secondary end points were quality-of-life, local recurrences, cosmetic results, and specific and overall rates of survival. The median follow-up was 30 months (range of 12 to 49 months), and median age was 72 years (range of 66 to 80 years). The median tumor diameter was 10 mm. All patients received the total prescribed dose. No acute grade 3 toxicities were observed. End points for all but 1 patient corresponded to acceptable quality index criteria. Pre-treatment quality-of-life scores were maximal, and no significant decrease was observed during follow-up. Cosmesis was good to excellent at 6 months. Two patients experienced recurrence but underwent salvage mastectomy. The authors concluded that these findings confirm that exclusive partial-breast IORT is feasible for treating early-stage breast cancer in the elderly. Intra-operative radiation therapy may be considered an alternative treatment for a selected population and offers a safe 1-step treatment.
In a prospective, randomized, non-inferiority trial, Vaidya et al (2010) compared targeted IORT versus whole breast radiotherapy for breast cancer. Women aged 45 years or older with invasive ductal breast carcinoma undergoing breast-conserving surgery were enrolled from 28 centers in 9 countries. Patients were randomly assigned in a 1:1 ratio to receive targeted IORT or whole breast EBRT, with blocks stratified by center and by timing of delivery of targeted IORT. Neither patients nor investigators or their teams were masked to treatment assignment. Post-operative discovery of pre-defined factors (e.g., lobular carcinoma) could trigger addition of EBRT to targeted IORT (in an expected 15 % of patients). The primary outcome was local recurrence in the conserved breast. The pre-defined non-inferiority margin was an absolute difference of 2.5 % in the primary endpoint. All randomized patients were included in the intention-to-treat analysis. A total of 1,113 patients were randomly allocated to targeted IORT and 1,119 were allocated to EBRT. Of 996 patients who received the allocated treatment in the targeted IORT group, 854 (86 %) received targeted IORT only and 142 (14 %) received targeted IORT plus EBRT. In the EBRT group, 1,025 (92 %) patients received the allocated treatment. At 4 years, there were 6 local recurrences in the IORT group and 5 in the EBRT group. The Kaplan-Meier estimate of local recurrence in the conserved breast at 4 years was 1.20 % (95 % confidence interval [CI]: 0.53 to 2.71) in the targeted IORT and 0.95 % (0.39 to 2.31) in the EBRT group (difference between groups 0.25 %, -1.04 to 1.54; p = 0.41). The frequency of any complications and major toxicity was similar in the 2 groups (for major toxicity, targeted IORT, 37 [3.3 %] of 1,113 versus EBRT, 44 [3.9 %] of 1,119; p = 0.44). Radiotherapy toxicity (Radiation Therapy Oncology Group grade 3) was lower in the targeted IORT group (6 patients [0.5 %]) than in the external EBRT group (23 patients [2.1 %]; p = 0.002). The authors concluded that for selected patients with early breast cancer, a single dose of radiotherapy delivered at the time of surgery by use of targeted IORT should be considered as an alternative to EBRT delivered over several weeks.
Wenz and associates (2010) developed a novel approach to deliver IORT during kyphoplasty and reported the first treated case, which dealt with a 60-year old patient with metastasizing breast cancer who under chemotherapy and later presented with a newly diagnosed painful metastasis in the 12th thoracic vertebra. Under general anesthesia, a bi-pedicular approach into the vertebra was chosen with insertion of specially designed metallic sleeves to guide the electron drift tube of the miniature X-ray generator. This was inserted with a novel sheet designed for this approach protecting the drift tube. A radiation dose of 8 Gy in 5-mm distance (50 kV X-rays) was delivered. The kyphoplasty balloons were inflated after IORT and polymethylmethacrylate cement was injected. The whole procedure lasted less than 90 minutes. The authors concluded that this novel, minimally invasive procedure can be performed in standard operating rooms and may become a valuable option for patients with vertebral metastases providing immediate stability and local control. They noted that a phase I/II study is under way to establish the optimal dosage.
Marchioro et al (2012) noted that intra-operative electron beam radiotherapy (IOERT) for prostate cancer is a radiotherapeutic technique, giving high- doses of radiation during radical prostatectomy (RP). These investigators presented the published treatment approaches for IORT analyzing functional outcome, morbidity, and oncological outcome in patients with clinical intermediate-high-risk prostate cancer. A systematic review of the literature was performed, searching PubMed and Web of Science. A "free text" protocol using the term intraoperative radiotherapy and prostate cancer was applied. A total of 10 records were retrieved and analyzed including more than 150 prostate cancer patients treated with IOERT. The authors concluded that IOERT represents a feasible technique with acceptable surgical time and minimal toxicity. They stated that a greater number of cases and longer follow-up time are needed in order to assess the long-term side effects and oncological outcome.
Ruano-Ravina et al (2012) evaluated the safety and effectiveness of IORT for early breast cancer through a systematic review. A total of 15 studies met the inclusion criteria. Most studies assessed the combined treatment with IORT (10 to 24 Gy) and EBRT (45 to 50 Gy) on early stage breast cancer (T(0-2)). Local control was over 95 % for 1 and 4 years of follow-up and the 5-year OS was 99 %. The TARGIT-A study found a similar survival comparing IORT with standard treatment. The incidence of acute and chronic complications was scarce. IORT is well-tolerated by patients and acute and late toxicities are low. There are no differences in survival for IORT-treated patients versus standard treatment.
Zurrida et al (2012) stated that wide tumor resection plus post-operative whole breast irradiation is standard treatment for early breast cancer. Irradiation decreases recurrence rates, but may cause poor cosmesis, breast pain, and cardiac and lung toxicity. Accelerated partial breast irradiation is increasingly used in the hope of increasing convenience, decreasing sequelae and maintaining cure rates. Intra-operative radiotherapy with electrons is an attractive accelerated partial breast irradiation technique because collimator placement is under the direct control of the surgeon who removes the tumor, the skin is spared, shielding protects the chest wall and complete irradiation can be given in a single intra-operative session (avoiding 5 to 7 weeks of whole breast irradiation). The authors concluded that IORT with electrons seems as safe as whole breast irradiation; however, long-term results on local control and survival are not available yet.
The American College of Radiology (ACR)'s Appropriateness Criteria® on "Conservative surgery and radiation -- stage I and II breast carcinoma" (Bellon et al, 2011) stated that "[t]here has also been interest in single-fraction intraoperative radiation therapy (using either electrons or low-energy photons). At present, however, there are very limited follow-up data, and this remains an experimental approach. Accrual is ongoing to a phase III trial cosponsored by the National Surgical Bowel and Breast Program and the Radiation Therapy Oncology Group (RTOG®) randomizing patients with stage 0-II cancer who have undergone lumpectomy to either whole-breast irradiation or PBI. There are other randomized trials ongoing in Canada and Europe examining this question, but their results are several years away".
Hershko et al (2012) described their experience with intra-operative electron radiotherapy (IOeRT) at the Rambam Health Care Campus in Haifa since they began utilizing this modality in 2006. From April 2006 to September 2010, 31 patients affected by unifocal invasive duct breast carcinoma less than or equal to 2 cm diameter received wide local resection followed by intra-operative radiotherapy with electrons. Patients were evaluated for early and late complications, and other events, 1 month after surgery and every 3 months thereafter for the duration of the first 2 years. After a mean follow-up of 36 months, 7 patients developed mild breast fibrosis and 3 suffered from mild post-operative infection. Rib fractures were observed in 4 patients before routine lead shielding was initiated. Additional whole-breast irradiation was given to 4 patients. None of the patients developed local recurrences or other ipsilateral cancers. Similarly, no contralateral cancers or distant metastases were observed. The authors concluded that intra-operative electron radiotherapy may be an alternative to external beam radiation therapy in an appropriate selected group of early-stage breast cancer patients. Moreover, they stated that long-term results of clinical trials are required to better evaluate the indications and utility of this technique in the management of breast cancer.
Leonardi et al (2012) evaluated late toxicity and cosmetic outcome after intra-operative radiotherapy using electrons (ELIOT) as sole treatment modality in early breast cancer patients. A total of 119 patients selected randomly among 1,200 cases was analyzed. Late toxicities were documented using the LENT-SOMA scoring system, cosmesis was evaluated with the Harvard scale, and a numeric rating scale was used to assess symptoms. After a median follow-up of 71 months, grade II fibrosis was observed in 38 patients (31.9 %) and grade III fibrosis in 7 patients (5.9 %). Post-operative complications (12.6 %) did not correlate with late toxicity. Physicians and patients scored cosmesis as excellent or good in 84 % and 77.3 % of the cases, respectively. Patient satisfaction was higher than 90 %. The authors concluded that in the study, ELIOT gives low and acceptable long-term toxicity. They stated that a longer follow-up and a larger number of patients are needed to confirm these promising results.
Maluta et al (2012) reported the results of a single-institution, phase II trial of accelerated partial breast irradiation (APBI) using a single dose of intraoperative electron radiation therapy (IOERT) in patients with low-risk early stage breast cancer. A cohort of 226 patients with low-risk, early stage breast cancer were treated with local excision and axillary management (sentinel node biopsy with or without axillary node dissection). After the surgeon temporarily re-approximated the excision cavity, a dose of 21 Gy using IOERT was delivered to the tumor bed, with a margin of 2 cm laterally. With a mean follow-up of 46 months (range of 28 to 63 months), only 1 case of local recurrence was reported. The observed toxicity was considered acceptable. The authors concluded that APBI using a single dose of IOERT can be delivered safely in women with early, low-risk breast cancer in carefully selected patients. Moreover, they stated that a longer follow-up is needed to ascertain its efficacy compared to that of the current standard treatment of whole-breast irradiation.
Sawaki et al (2012) stated that IORT is under evaluation in breast-conserving surgery because the feasibility of the IORT procedure including transportation of the patient under general anesthesia is not well-established. Thus, this prospective single-center pilot study aimed to test the feasibility of IORT at a single dose of 21 Gy in Japanese breast cancer patients. The primary endpoint was early toxicity; the secondary endpoint was late toxicity. Patients with histologically or cytologically proven primary early breast cancer were eligible. Inclusion criteria were as follows: (i) T < 2.5 cm; (ii) desire for breast-conserving surgery; (iii) age greater than 50 years; (iv) surgical margin greater than 1 cm; (v) intra-operative pathologically free margins; and (vi) sentinel node negative. Exclusion criteria were (i) contraindications to radiation therapy; (ii) past radiation therapy for the same breast or chest; (iii) extensive intra-ductal component; and (iv) a tumor located in the axillary tail of the breast. All patients gave written informed consent. Partial resection was performed with at least a margin of 1 cm around the tumor. The patient was transported from the surgical suite to the radiation room. Radiation at 21 Gy was delivered directly to the mammary gland. Toxicity was evaluated with the Common Terminology Criteria for Adverse Events V4.0. A total of 5 patients were enrolled in this pilot study and received 21 Gy. Follow-up ranged from 7.8 to 11.0 months (median of 10.2). Intraoperative transportation to the radiation room during the surgical procedure under general anesthesia was performed safely in all patients. Treatment-related toxicities within 3 months were deep connective tissue fibrosis (grade 1, n = 3) and pain (grade 1, n = 3). There was no case of wound infection, wound dehiscence, or soft tissue necrosis. Overall, there was no severe adverse event. The authors concluded that the procedure was tolerated very well in this first group of Japanese female patients treated with IORT, as was the case with European women. They stated that a longer follow-up is needed for the evaluation of any potential late side effects or recurrences; and a phase II study is now being conducted for the next group of patients.
Engel et al (2013) noted IORT with low-energy x-rays is increasingly used in breast-conserving therapy (BCT). Previous non-randomized studies have observed mammographic changes in the tumor bed to be more pronounced after IORT. The purpose of this study was to re-assess the post-operative changes in a randomized single-center subgroup of patients from a multi-center trial (TARGIT-A). In this subgroup (n = 48) 27 patients received BCT with IORT, 21 patients had BCT with standard whole-breast radiotherapy serving as controls. Overall 258 post-operative mammograms (median follow-up of 4.3 years, range of 3 to 8) were retrospectively evaluated by 2 radiologists in consensus focusing on changes in the tumor bed. Fat necroses showed to be significantly more frequent (56 % versus 24 %) and larger (8.7 versus 1.6 sq cm, median) after IORT than those in controls. Scar calcifications were also significantly more frequent after IORT (63 % versus 19 %). The authors stated that the high incidence of large fat necroses in this study confirmed previous study findings. However, the overall higher incidence of calcifications in the tumor bed after IORT represents a new finding, requiring further attention.
Vanderwalde et al (2013) performed a phase II study of pre-excision IORT for early-stage breast cancer. Patients greater than or equal to 48 years of age with invasive ductal carcinoma, less than or equal to 3 cm, and clinically node-negative were eligible for this study, which was approved by institutional review board. Ultrasound was used to select electron energy and cone size to cover the tumor plus 1.5 to 2.0 cm lateral margins and 1 cm deep margins (90 % isodose). Fifteen Gy was delivered with a Mobetron irradiator, and immediate needle-localized partial mastectomy followed. Local event results were updated using the Kaplan-Meier method. A total of 53 patients received IORT alone. Median age was 63 years, and median tumor size was 1.2 cm. Of these, 81 % were positive for estrogen receptor or progesterone receptor, 11 % were positive for human epidermal growth factor receptor 2, and 15 % were triple-negative. Also, 42 %, 49 %, and 9 % would have fallen into the Suitable, Cautionary, and Unsuitable groups, respectively, of the American Society of Therapeutic Radiation Oncology consensus statement for accelerated partial breast irradiation. Median follow-up was 69 months. Ipsilateral events occurred in 8 of 53 patients. The 6-year actuarial rate of ipsilateral events was 15 % (95 % CI: 7 % to 29 %). The crude event rate for Suitable and Cautionary groups was 1 of 22 (5 %) and 7 of 26 (27 %), respectively. Overall survival was 94.4 %, and breast cancer-specific survival was 100 %. The authors concluded that the rate of local events in this study is a matter of concern, especially in the Cautionary group. On the basis of these findings, pre-excision IORT, as delivered in this study, may not provide adequate local control for less favorable early-stage breast cancers.
An UpToDate review on “Role of radiation therapy in breast conservation therapy” (Pierce and Sabel, 2013) does not mention the use of IORT as a management tool. Furthermore, the NCCN’s clinical practice guideline on “Breast cancer” (Version 3.2013) does not mention IORT as a management fool for breast conservation.
Zygogianni et al (2012) noted that pancreatic cancer is rarely curable, and the OS rate at 5 years is under 4 %. This study aimed to assess the efficacy, effectiveness and safety of IORT as treatment in pancreatic cancer, by means of a systematic review of the literature. These investigators searched Pubmed from 1980 until 2010 by means of prospective randomized trials. The aim was to assess the potential impact of IORT on local control, quality of life and OS. The search was restricted to articles published in English. Intra-operative radiation therapy offers the opportunity to administer high-doses of irradiation to areas of neoplastic involvement while attempting simultaneously to spare normal tissues in the region from potentially damaging radiation exposure. However, the results were not in favor of IORT in the case of pancreatic cancer in locally advanced and metastatic stages. The authors concluded that there is no clear evidence to indicate that IORT is more effective than other therapies in treating pancreatic cancer.
Niewald et al (2009) retrospectively evaluated the results after a regimen of surgery, IORT, and external beam radio-therapy (EBRT) for soft-tissue sarcomas. A total of 38 consecutive patients underwent IORT for soft-tissue sarcoma; 29 were treated for primary tumors, 9 for recurrences. There were 14 cases with liposarcomas, 8 with leiomyosarcomas, 7 with malignant fibrous histiocytomas; 27/38 tumors were located in the extremities, the remaining ones in the retro-peritoneum or the chest. Radical resection was attempted in all patients; a R0-resection was achieved in 15/38 patients, R1 in 12/38 pats and R2 in 4/38 pats. IORT was performed using a J-125 source and a HDR (high dose rate) after-loading machine after suturing silicone flaps to the tumor bed. The total dose applied ranged from 8-15 Gy/0.5 cm tissue depth measured from the flap surface. After wound healing, EBRT was applied in 31/38 patients with total doses of 23-56 Gy dependent on resection status and wound situation. The mean duration of follow-up was 2.3 years. A local recurrence was found in 10/36 patients, lymph node metastases in 2/35, and distant metastases in 6/35 patients. The actuarial local control rate was 63 %/5 years. The overall survival rate was 57 %/5 years. There was no statistically significant difference between the results after treatment for primaries or for recurrences. Late toxicity to the skin was found in 13/31 patients, wound healing problems in 5/31 patients. A neuropathy was never seen. The authors concluded that the combination of surgery, IORT, and EBRT yields favorable local control and survival data, which were well within the range of the results reported in the literature. The complication rates, however, are considerable although the complications are not severe, they should be taken into account when therapy decisions are made.
Call et al (2012) reviewed outcomes for patients who received IORT for upper-extremity sarcoma. These investigators identified patients with upper-extremity tumors who were treated with EBRT, surgery, and IORT, with or without chemotherapy. Kaplan-Meier estimates for overall survival (OS), central control (CC), local control (LC), and distant control (DC) were obtained. A total of 61 patients were identified. Median age was 50 years (range of 13 to 95 years). Median follow-up was 5.9 years. Eleven patients had gross (R2; n = 1) or microscopic (R1; n = 10) disease at the time of IORT. IORT doses ranged from 7.50 to 20.00 Gy. External beam radiotherapy doses ranged from 19.80 to 54.00 Gy. OS at 5 and 10 years was 72 % and 58 %, respectively. LC at 5 and 10 years was 91% and 88%, respectively. DC at 5 and 10 years was 80% and 77%, respectively. Patients treated for recurrent disease had inferior 5-year OS compared with patients with first diagnoses (63% vs. 74%; P=0.02) and lower 5-year LC (67 % versus 94 %; p < 0.01). For patients with R1 or R2 resections, LC at 5 and 10 years was 100 % and 86 %, respectively; for patients with R0 resections, LC was 89 % at both 5 and 10 years (p = 0.98). Severe toxicity attributable to treatment was noted for 4 patients (7 %). The authors concluded that for upper-extremity sarcoma, treatment including IORT was associated with excellent LC, limb preservation, and survival. LC rates were excellent for patients with positive margins after resection. Patients with recurrent disease had worse outcomes, but limb preservation was achievable for most patients.
An UpToDate review on “Local treatment for primary soft tissue sarcoma of the extremities and chest wall” (Delaney et al, 2013) states that “For patients treated preoperatively, 50 Gy is administered in 25 fractions over five weeks followed three to four weeks later by a conservative resection. A boost dose to 66 Gy may be given postoperatively or intraoperatively for microscopically positive margins and to 75 Gy if there is gross residual disease. In patients with frozen section evidence of close or positive margins, a boost can be delivered by placement of brachytherapy catheters or intraoperative electron beam radiation therapy”.
Also, NCCN’s clinical practice guideline on “Soft tissue sarcoma” (Version 1.2013) states that “Advances in RT technology such as brachytherapy, intensity-modulated radiation therapy (IMRT), and intraoperative radiation therapy (IORT) have led to the improvement of treatment outcomes in patients with STS”.
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