{"entity":{"id":"nsabp-b39","kind":"trial","name":"NSABP B-39/RTOG 0413","aka":[],"tldr":"The largest partial-breast trial found recurrence rates within one percentage point of whole-breast treatment but could not formally prove equivalence, so accelerated partial-breast irradiation is offered to selected lower-risk women rather than everyone.","summary":"NSABP B-39/RTOG 0413 randomised 4,216 women with stage 0 to II breast cancer to whole-breast irradiation or accelerated partial-breast irradiation given twice daily over five to ten days by brachytherapy or external beam. Ten-year ipsilateral breast tumour recurrence was 4.6 percent with partial-breast and 3.9 percent with whole-breast treatment; the hazard ratio's confidence interval crossed the equivalence margin, so equivalence was not established, although the absolute difference was small (Vicini and colleagues, Lancet 2019).","status":"negative","asOf":"2026-09-16","links":[{"label":"ClinicalTrials.gov NCT00103181","url":"https://clinicaltrials.gov/study/NCT00103181"},{"label":"Lancet 2019","url":"https://doi.org/10.1016/S0140-6736(19)32514-0"}],"tags":["radiation-wave2"],"related":[],"cancers":["breast-hr-positive","breast-her2-positive","tnbc","ductal-carcinoma-in-situ","breast-cancer"],"sections":[],"technologies":["hdr-brachytherapy","imrt-igrt"],"targets":[],"drugs":[],"companies":["nrg-oncology"],"institutions":[],"pathways":[],"terms":["partial-breast-irradiation"],"trials":["rapid","targit-a"],"people":[],"bottlenecks":[],"keyPapers":["paper-nsabp-b39-lancet-2019"],"journals":[],"dependsOn":[],"notes":[],"nct":"NCT00103181","phase":"3","setting":"Early breast cancer or DCIS after lumpectomy: accelerated partial-breast irradiation (twice daily over one week) versus whole-breast irradiation","sponsor":"NRG Oncology (NSABP and RTOG)","result":"10-year ipsilateral breast tumour recurrence 4.6% (partial breast) vs 3.9% (whole breast); equivalence not established.","started":"2005-03","yearReported":2019,"enrolled":4216,"enrolledBasis":"registry","outcomes":[{"endpoint":"Ipsilateral breast tumour recurrence at 10 years","primary":true,"unit":"%","arms":[{"name":"Accelerated partial-breast irradiation","n":2107,"value":4.6},{"name":"Whole-breast irradiation","n":2109,"value":3.9}]}]},"route":"/trials/nsabp-b39/","neighbours":{"cancer":[{"id":"breast-cancer","kind":"cancer","name":"Breast cancer (all types)","route":"/cancers/breast-cancer/"},{"id":"ductal-carcinoma-in-situ","kind":"cancer","name":"Ductal carcinoma in situ (DCIS)","route":"/cancers/ductal-carcinoma-in-situ/"},{"id":"breast-her2-positive","kind":"cancer","name":"HER2-positive breast cancer","route":"/cancers/breast-her2-positive/"},{"id":"breast-hr-positive","kind":"cancer","name":"HR-positive / HER2-negative breast cancer","route":"/cancers/breast-hr-positive/"},{"id":"tnbc","kind":"cancer","name":"Triple-negative breast cancer (TNBC)","route":"/cancers/tnbc/"}],"technology":[{"id":"hdr-brachytherapy","kind":"technology","name":"High-dose-rate brachytherapy","route":"/technologies/hdr-brachytherapy/"},{"id":"imrt-igrt","kind":"technology","name":"IMRT / IGRT (modern external beam)","route":"/technologies/imrt-igrt/"}],"company":[{"id":"nrg-oncology","kind":"company","name":"NRG Oncology","route":"/companies/nrg-oncology/"}],"term":[{"id":"partial-breast-irradiation","kind":"term","name":"Partial-breast irradiation","route":"/terms/partial-breast-irradiation/"}],"trial":[{"id":"rapid","kind":"trial","name":"RAPID (accelerated partial-breast irradiation)","route":"/trials/rapid/"},{"id":"targit-a","kind":"trial","name":"TARGIT-A (targeted intraoperative radiotherapy)","route":"/trials/targit-a/"}],"paper":[{"id":"paper-nsabp-b39-lancet-2019","kind":"paper","name":"Long-term primary results of accelerated partial breast irradiation after breast-conserving surgery for early-stage breast cancer: a randomised, phase 3, equivalence trial","route":"/key-papers/paper-nsabp-b39-lancet-2019/"}]}}