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Background: Whole-breast irradiation after breast-conserving surgery for patients with early-stage breast cancer decreases ipsilateral breast-tumour recurrence (IBTR), yielding comparable results to mastectomy. It is unknown whether accelerated partial breast irradiation (APBI) to only the tumour-bearing quadrant, which shortens treatment duration, is equally effective. In our trial, we investigated whether APBI provides equivalent local tumour control after lumpectomy compared with whole-breast irradiation., Methods: We did this randomised, phase 3, equivalence trial (NSABP B-39/RTOG 0413) in 154 clinical centres in the USA, Canada, Ireland, and Israel. Adult women (>18 years) with early-stage (0, I, or II; no evidence of distant metastases, but up to three axillary nodes could be positive) breast cancer (tumour size ≤3 cm; including all histologies and multifocal breast cancers), who had had lumpectomy with negative (ie, no detectable cancer cells) surgical margins, were randomly assigned (1:1) using a biased-coin-based minimisation algorithm to receive either whole-breast irradiation (whole-breast irradiation group) or APBI (APBI group). Whole-breast irradiation was delivered in 25 daily fractions of 50 Gy over 5 weeks, with or without a supplemental boost to the tumour bed, and APBI was delivered as 34 Gy of brachytherapy or 38·5 Gy of external bream radiation therapy in 10 fractions, over 5 treatment days within an 8-day period. Randomisation was stratified by disease stage, menopausal status, hormone-receptor status, and intention to receive chemotherapy. Patients, investigators, and statisticians could not be masked to treatment allocation. The primary outcome of invasive and non-invasive IBTR as a first recurrence was analysed in the intention-to-treat population, excluding those patients who were lost to follow-up, with an equivalency test on the basis of a 50% margin increase in the hazard ratio (90% CI for the observed HR between 0·667 and 1·5 for equivalence) and a Cox proportional hazard model. Survival was assessed by intention to treat, and sensitivity analyses were done in the per-protocol population. This trial is registered with ClinicalTrials.gov, NCT00103181., Findings: Between March 21, 2005, and April 16, 2013, 4216 women were enrolled. 2109 were assigned to the whole-breast irradiation group and 2107 were assigned to the APBI group. 70 patients from the whole-breast irradiation group and 14 from the APBI group withdrew consent or were lost to follow-up at this stage, so 2039 and 2093 patients respectively were available for survival analysis. Further, three and four patients respectively were lost to clinical follow-up (ie, survival status was assessed by phone but no physical examination was done), leaving 2036 patients in the whole-breast irradiation group and 2089 in the APBI group evaluable for the primary outcome. At a median follow-up of 10·2 years (IQR 7·5-11·5), 90 (4%) of 2089 women eligible for the primary outcome in the APBI group and 71 (3%) of 2036 women in the whole-breast irradiation group had an IBTR (HR 1·22, 90% CI 0·94-1·58). The 10-year cumulative incidence of IBTR was 4·6% (95% CI 3·7-5·7) in the APBI group versus 3·9% (3·1-5·0) in the whole-breast irradiation group. 44 (2%) of 2039 patients in the whole-breast irradiation group and 49 (2%) of 2093 patients in the APBI group died from recurring breast cancer. There were no treatment-related deaths. Second cancers and treatment-related toxicities were similar between the two groups. 2020 patients in the whole-breast irradiation group and 2089 in APBI group had available data on adverse events. The highest toxicity grade reported was: grade 1 in 845 (40%), grade 2 in 921 (44%), and grade 3 in 201 (10%) patients in the APBI group, compared with grade 1 in 626 (31%), grade 2 in 1193 (59%), and grade 3 in 143 (7%) in the whole-breast irradiation group., Interpretation: APBI did not meet the criteria for equivalence to whole-breast irradiation in controlling IBTR for breast-conserving therapy. Our trial had broad eligibility criteria, leading to a large, heterogeneous pool of patients and sufficient power to detect treatment equivalence, but was not designed to test equivalence in patient subgroups or outcomes from different APBI techniques. For patients with early-stage breast cancer, our findings support whole-breast irradiation following lumpectomy; however, with an absolute difference of less than 1% in the 10-year cumulative incidence of IBTR, APBI might be an acceptable alternative for some women., Funding: National Cancer Institute, US Department of Health and Human Services., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Purpose: To update the accelerated partial breast irradiation Consensus Statement published in 2009 and provide guidance on use of intraoperative radiation therapy (IORT) for partial breast irradiation in early-stage breast cancer, based on published evidence complemented by expert opinion., Methods and Materials: A systematic PubMed search using the same terms as the original Consensus Statement yielded 419 articles; 44 articles were selected. The authors synthesized the published evidence and, through a series of conference calls and e-mails, reached consensus regarding the recommendations., Results: The new recommendations include lowering the age in the "suitability group" from 60 to 50 years and in the "cautionary group" to 40 years for patients who meet all other elements of suitability (Table 1). Patients with low-risk ductal carcinoma in situ, as per Radiation Therapy Oncology Group 9804 criteria, were categorized in the "suitable" group. The task force agreed to maintain the current criteria based on margin status. Recommendations for the use of IORT for breast cancer patients include: counseling patients regarding the higher risk of ipsilateral breast tumor recurrence with IORT compared with whole breast irradiation; the need for prospective monitoring of long-term local control and toxicity with low-energy radiograph IORT given limited follow-up; and restriction of IORT to women with invasive cancer considered "suitable.", Conclusion: These recommendations will provide updated clinical guidance regarding use of accelerated partial breast irradiation for radiation oncologists and other specialists participating in the care of breast cancer patients., (Copyright © 2016 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.)

Purpose: To examine 10-year rates of local, regional, and distant recurrences, patterns of recurrence, and survival rates for breast cancer patients enrolled on Study NRG Oncology/Radiation Therapy Oncology Group 9517, a multi-institutional prospective trial that studied one of the earliest methods of accelerated partial breast irradiation (APBI), multicatheter brachytherapy (MCT)., Methods and Materials: Eligibility included stage I/II unifocal breast cancer <3 cm in size after lumpectomy with negative surgical margins and 0 to 3 positive axillary nodes without extracapsular extension. The APBI dose delivered was 34 Gy in 10 twice-daily fractions over 5 days for high-dose-rate (HDR); and 45 Gy in 3.5 to 5 days for low-dose-rate (LDR) brachytherapy. The primary endpoint was HDR and LDR MCT reproducibility. This analysis focuses on long-term ipsilateral breast recurrence (IBR), contralateral breast cancer events (CBE), regional recurrence (RR), and distant metastases (DM), disease-free, and overall survival., Results: The median follow-up was 12.1 years. One hundred patients were accrued from 1997 to 2000; 98 were evaluable; 65 underwent HDR and 33 LDR MCT. Median age was 62 years; 88% had T1 tumors; 81% were pN0. Seventy-seven percent were estrogen receptor and/or progesterone receptor positive; 33% received adjuvant chemotherapy and 64% antiendocrine therapy. There have been 4 isolated IBRs and 1 IBR with RR, for 5.2% 10-year IBR without DM. There was 1 isolated RR, 1 with IBR, and 1 with a CBE, for 3.1% 10-year RR without DM. The 10-year CBE rate was 4.2%, with 5 total events. Eleven patients have developed DM, 8 have died of breast cancer, and 22 have died from other causes. The 10-year DFS and OS rates are 69.8% and 78.0%, respectively., Conclusion: This multi-institutional, phase 2 trial studying MCT-APBI continues to report durable in-breast cancer control rates with long-term follow-up., Competing Interests: R.R.K. reports other support from Cianna Medical, grants from Elekta, outside the submitted work., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Purpose: Brachytherapy is a method for delivering partial-breast irradiation after breast-conserving surgery (BCS). It is currently used in the community setting, although its efficacy has yet to be validated in prospective comparative trials. Frequency and factors influencing use have not been previously identified., Methods: In a nationwide database of 6,882 Medicare beneficiaries (age ≥ 65 years) with private supplemental insurance (MarketScan Medicare Supplemental), claims codes identified patients treated with brachytherapy versus external-beam radiation after BCS for incident breast cancer (diagnosed from 2001 to 2006). Logistic regression modeled predictors of brachytherapy use., Results: Frequency of brachytherapy use as an alternative to external-beam radiation after BCS increased over time (< 1% in 2001, 2% in 2002, 3% in 2003, 5% in 2004, 8% in 2005, 10% in 2006; P < .001). Increased use correlated temporally with US Food and Drug Administration approval and Medicare reimbursement of brachytherapy technology. Brachytherapy use was more likely in women with lymph node-negative disease (odds ratio [OR], 2.19; 95% CI, 1.17 to 4.11) or axillary surgery (OR, 1.74; 95% CI, 1.23 to 2.44). Brachytherapy use was also more likely in women with non-health maintenance organization insurance (OR, 1.81; 95% CI, 1.24 to 2.64) and in areas with higher median income (OR, 1.58; 95% CI, 1.05 to 2.38), lower density of radiation oncologists (OR, 1.78; 95% CI, 1.11 to 2.86), or higher density of surgeons (OR, 1.57; 95% CI, 1.07 to 2.31)., Conclusion: Despite ongoing questions regarding efficacy, breast brachytherapy was rapidly incorporated into the care of older, insured patients. In our era of frequently emerging novel technologies yet growing demands to optimize costs and outcomes, results provide insight into how clinical, policy, and socioeconomic factors influence new technology diffusion into conventional care.

Purpose: Radiation Therapy Oncology Group 95-17 is a prospective Phase II cooperative group trial of accelerated partial breast irradiation (APBI) alone using multicatheter brachytherapy after lumpectomy in select early-stage breast cancers. Tumor control and survival outcomes are reported., Methods and Materials: Eligibility criteria included Stage I/II breast carcinoma confirmed to be <3 cm, unifocal, invasive nonlobular histology with zero to three positive axillary nodes without extracapsular extension. APBI treatment was delivered with either low-dose-rate (LDR) (45 Gy in 3.5-5 days) or high-dose-rate (HDR) brachytherapy (34 Gy in 10 twice-daily fractions over 5 days). End points evaluated included in-breast control, regional control, mastectomy-free rate, mastectomy-free survival, disease-free survival, and overall survival. The study was designed to analyze the HDR and LDR groups separately and without comparison., Results: Between 1997 and 2000, 100 patients were accrued and 99 were eligible; 66 treated with HDR brachytherapy and 33 treated with LDR brachytherapy. Eighty-seven patients had T1 lesions and 12 had T2 lesions. Seventy-nine were pathologically N0 and 20 were N1. Median follow-up in the HDR group is 6.14 years with the 5-year estimates of in-breast, regional, and contralateral failure rates of 3%, 5%, and 2%, respectively. The LDR group experienced similar results with a median follow-up of 6.22 years. The 5-year estimates of in-breast, regional, and contralateral failure rates of 6%, 0%, and 6%, respectively., Conclusion: Patients treated with multicatheter partial breast brachytherapy in this trial experienced excellent in-breast control rates and overall outcome that compare with reports from APBI studies with similar extended follow-up.

Purpose: The Radiation Therapy Oncology Group (RTOG) protocol 95-17 was a Phase I/II trial to evaluate multicatheter brachytherapy as the sole method of adjuvant breast radiotherapy for Stage I/II breast carcinoma after breast-conserving surgery. Low- or high-dose-rate sources were allowed. Dose prescription and treatment evaluation were based on recommendations in the International Commission on Radiation Units and Measurements (ICRU), Report 58 and included the parameters mean central dose (MCD), average peripheral dose, dose homogeneity index (DHI), and the dimensions of the low- and high-dose regions., Methods and Materials: Three levels of quality assurance were implemented: (1) credentialing of institutions was required before entering patients into the study; (2) rapid review of each treatment plan was conducted before treatment; and (3) retrospective review was performed by the Radiological Physics Center in conjunction with the study chairman and RTOG dosimetry staff., Results: Credentialing focused on the accuracy of dose calculation algorithm and compliance with protocol guidelines. Rapid review was designed to identify and correct deviations from the protocol before treatment. The retrospective review involved recalculation of dosimetry parameters and review of dose distributions to evaluate the treatment. Specifying both central and peripheral doses resulted in uniform dose distributions, with a mean dose homogeneity index of 0.83 +/- 0.06., Conclusions: Vigorous quality assurance resulted in a high-quality study with few deviations; only 4 of 100 patients were judged as representing minor variations from protocol, and no patient was judged as representing major deviation. This study should be considered a model for quality assurance of future trials.

Objective: Patients with early-stage invasive ductal breast cancer were prospectively evaluated using MammoSite RTS balloon brachytherapy (RTS Cytyc Corp, Marlborough, MA) as the sole modality for delivering accelerated partial breast irradiation to the lumpectomy bed with breast-conserving surgery. This report presents the 5-year results of the treated patients., Methods: From May 2000 to October 2001, 70 patients were enrolled in this prospective study. Forty-three patients completed accelerated partial breast irradiation with MammoSite brachytherapy following lumpectomy and axillary staging. Thirty-six patients have been followed for a median of 5.5 years (mean 65.2 months). Criteria for entry into the study were unifocal invasive ductal carcinoma, tumor size < or = 2 cm, age > or = 45 years, absence of extensive intraductal component, cavity size > or = 3 cm in 1 dimension, node-negative, and final margins negative per National Surgical Adjuvant Breast and Bowel Project definition. A minimum balloon-to-skin surface distance of 5 mm was required. A dose of 34 Gy was delivered in 10 fractions over 5 days prescribed to 1 cm from the applicator surface using iridium-192 high-dose-rate brachytherapy. Data on infection, seromas, cosmetic outcome, and toxicities were collected at 3 and 6 months and at yearly intervals. Local recurrences, both true recurrences in the lumpectomy bed and failures outside the initially treated target volume (elsewhere failures), were recorded. Contralateral breast failure rates were noted., Results: The catheter was not implanted in 16 of the 70 enrolled patients due to cavity size not amenable to balloon placement (n = 10), ineligible by criteria (n = 4), and skin spacing (n = 2). Fifty-four patients were implanted and 43 were successfully treated with MammoSite balloon brachytherapy. Reasons for catheter explantation in 11 patients were poor cavity conformance in 7, inadequate skin spacing in 2, positive node in 1 and age less than 45 years in 1. Of the 43 patients who completed treatment, the infection rate was 9.3%. Seroma formation occurred in 32.6% of patients, of which 12% were symptomatic requiring aspiration. Asymptomatic fat necrosis was identified in 4 of the 43 patients, noted from time of catheter removal at 11, 14, 42, and 63 months. Good-excellent cosmetic outcomes were achieved in 83.3% of the 36 patients with more than 5 years of follow-up. Cosmetic outcomes were improved, with increased skin spacing having statistical significance at skin spacing > or = 7 mm. The only serious adverse events were 2 infections: mastitis and abscess. Seven of the 43 treated patients have been discontinued from follow-up. None had a local recurrence recorded at last visit. Reasons for exit from the study were death from metastatic disease (n = 3), lost to follow-up (n = 2), and placed in hospice for other medical conditions (n = 2). No local recurrences (either at the tumor bed or elsewhere in the breast) or regional recurrences have occurred in the 36 patients who have been followed for a median of 5.5 years. No contralateral cancers have developed., Conclusions: MammoSite balloon brachytherapy as a sole modality for delivering radiation to the tumor bed has been successful in achieving excellent local control in this initial clinical study of patients with early-stage invasive ductal breast cancer. This has been achieved with minimal toxicities and good-excellent cosmetic outcomes in 83.3%. Accelerated partial breast irradiation using the MammoSite balloon in a carefully selected group of patients has demonstrated 5-year local recurrence results comparable to those achieved with conventional whole breast radiation therapy and interstitial catheter brachytherapy as reported at 5-year data points in studies of these treatment modalities. Poor cavity conformance and inadequate skin distance were the main factors limiting use of the MammoSite device. Extended follow-up will be required to determine the long-term efficacy of this treatment modality.

Background and Purpose: Accelerated partial breast irradiation (APBI) is being studied in a phase III randomized trial as an alternative to whole breast irradiation (WBI) for early stage breast cancer patients. There are three methods for APBI: multi-catheter brachytherapy (MCT), MammoSite brachytherapy (MST), or 3D conformal (3DCRT). There is a paucity of data comparing among methods. Using a linear-quadratic (LQ) model, we evaluated the anticipated efficacy among the APBI methods for equivalent uniform dose (EUD), Tumor Control Probability (TCP), and Normal Tissue Complication Probability (NTCP)., Materials and Methods: Treatment plans from five patients treated by each APBI modality were retrospectively selected. Dose-volume-histograms (DVH) for planning target volume (PTV), breast, and lung were generated. The LQ parameters alpha=0.3Gy(-1) and alpha/beta=10Gy were used for calculations. The values of EUD, TCP, and NTCP were calculated based on DVHs., Results: The average EUD (normalized to 3.4Gy BID) for the MCT, MST, and 3DCRT APBI was 35, 37.2, and 37.6Gy. When normalized to 2Gy fractionation these become, 42.2, 46.4, and 46.9Gy. Average TCP for MCT, MST, and 3DCRT PBI was 94.8%, 99.1%, and 99.2%. The NTCP values for breast and lung were low for all three methods., Conclusions: The EUD for PTV and TCP were most similar in MST and 3DCRT APBI and were lower in MCT APBI. This questions the equivalence of the three APBI modalities that are currently being evaluated in the NSABP-B39/RTOG 0413 protocol.

Purpose: Accelerated partial breast irradiation (APBI) can be delivered with brachytherapy within 4-5 days compared with 5-6 weeks for conventional whole breast external beam radiotherapy. Radiation Therapy Oncology Group 95-17 is the first prospective phase I-II cooperative group trial of APBI alone after lumpectomy in select patients with breast cancer. The toxicity rates are reported for low-dose-rate (LDR) and high-dose-rate (HDR) APBI on this trial., Methods and Materials: The inclusion criteria for this study included invasive nonlobular tumors < or =3 cm after lumpectomy with negative surgical margins and axillary dissection with zero to three positive axillary nodes without extracapsular extension. The patients were treated with either LDR APBI (45 Gy in 3.5-5 days) or HDR APBI (34 Gy in 10 twice-daily fractions within 5 days). Chemotherapy (> or =2 weeks after APBI) and/or tamoxifen could be given at the discretion of the treating physicians., Results: Between August 1997 and March 2000, 100 women were enrolled in this study, and 99 were evaluated. Of the 99 women, 33 were treated with LDR and 66 with HDR APBI. The median follow-up for all patients was 2.7 years (range, 0.6-4.4 years) and was 2.9 years for LDR and 2.7 years for HDR patients. Toxicities attributed to APBI included erythema, edema, tenderness, pain, and infection. Of the 66 patients treated with HDR APBI, 2 (3%) had Grade 3 or 4 toxicity. Of the 33 patients treated with LDR, 3 (9%) had Grade 3 or 4 toxicity during brachytherapy. Late toxicities included skin thickening, fibrosis, breast tenderness, and telangiectasias. No patient experienced late Grade 4 toxicity; the rate of Grade 3 toxicity was 18% for the LDR and 4% for the HDR groups., Conclusion: Acute and late toxicity for this invasive breast radiation technique was modest and acceptable. Patients receiving chemotherapy, a nonprotocol therapy, had a greater rate of Grade 3 toxicity. The study design did not allow for this to be tested statistically.

Purpose: We present the results of the initial clinical testing of the MammoSite balloon breast brachytherapy applicator in women with early-stage breast cancer treated with breast-conserving therapy., Methods and Materials: Seventy patients were enrolled in a multicenter prospective trial testing the applicator for safety and performance. Fifty-four patients were implanted, and 43 patients were ultimately eligible for and received brachytherapy as the sole radiation modality after lumpectomy. Patients were staged T1N0M0 with negative pathologic margins and age >45 years. A dose of 34 Gy was delivered in 10 fractions over 5 days prescribed to 1 cm from the applicator surface using 192Ir high-dose-rate brachytherapy. A minimum skin-to-balloon surface distance of 5 mm was required for treatment. Device performance, complications, and cosmesis were assessed., Results: Computed tomography imaging post-balloon inflation showed 8, 14, and 21 patients with 5-6 mm, 7-9 mm, and >10 mm of skin spacing, respectively. Two patients were explanted because of inadequate skin spacing and 7 because of suboptimal conformance of the surgical cavity to the applicator balloon. One patient was explanted because of positive nodal status and another because of age. The most common side effects related to device placement included mild erythema, drainage, pain, and echymosis. No severe side effects related to implantation, brachytherapy, or explantation occurred. Side effects related to radiation therapy were generally mild with erythema, pain, and dry desquamation being the most common. At 1 month, 88% of patients were evaluated as having good-to-excellent cosmetic results., Conclusions: The MammoSite balloon breast brachytherapy applicator performed well clinically. All eligible patients completed treatment. Side effects were mild to moderate and self-limiting. Skin-balloon surface distance and balloon-cavity conformance were the main factors limiting the initial use of the device.