{"entity":{"id":"nsabp-b51","kind":"trial","name":"NSABP B-51 / RTOG 1304","aka":["NSABP B-51","RTOG 1304","NRG Oncology/NSABP B-51"],"tldr":"If chemotherapy given before surgery clears the lymph nodes completely, irradiating those nodes afterwards adds nothing. Fewer than one woman in ten had the cancer come back either way, and the difference between the two groups was within chance.","summary":"B-51 asked whether the response to chemotherapy, rather than the stage at diagnosis, should decide the radiotherapy. Patients with clinical T1 to T3, N1, M0 breast cancer and biopsy-proven axillary disease who reached pathologically node-negative status after chemotherapy were randomised to regional nodal irradiation or to none. 1,641 were enrolled and 1,556 were analysed, 772 in the irradiation group and 784 without.\n\nAfter a median 59.5 months there had been 109 primary endpoint events, 50 in the irradiation group and 59 without. Regional nodal irradiation did not significantly lengthen the invasive breast cancer recurrence-free interval (hazard ratio 0.88, 95 percent confidence interval 0.60 to 1.28, p=0.51), and the point estimates of survival free from those events were 92.7 and 91.8 percent. It did not improve the locoregional recurrence-free interval, the distant recurrence-free interval, disease-free survival or overall survival. No deaths were attributed to the protocol therapy; grade 4 adverse events occurred in 0.5 percent of the irradiation group and 0.1 percent of the other.\n\nThis is a negative trial in the useful sense: it removes a treatment. Roughly four in ten patients with node-positive disease at diagnosis reach a complete nodal response with modern chemotherapy, and for those patients B-51 says the nodes can be left alone. It is the radiotherapy counterpart of what ATNEC is asking about surgery.","status":"negative","asOf":"2026-09-25","links":[{"label":"ClinicalTrials.gov NCT01872975","url":"https://clinicaltrials.gov/study/NCT01872975"},{"label":"NSABP B-51/RTOG 1304 (New England Journal of Medicine 2025)","url":"https://doi.org/10.1056/NEJMoa2414859"}],"tags":[],"related":[],"cancers":["breast-cancer","breast-hr-positive","breast-her2-positive","tnbc"],"sections":[],"technologies":["imrt-igrt"],"targets":[],"drugs":[],"companies":["nrg-oncology","nsabp-foundation"],"institutions":[],"pathways":[],"terms":["neoadjuvant-versus-adjuvant-breast","targeted-axillary-dissection","post-mastectomy-radiotherapy","pcr"],"trials":["atnec","acosog-z1071","supremo","ma-20"],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"nct":"NCT01872975","phase":"3","setting":"Clinical T1 to T3, N1, M0 breast cancer with biopsy-proven axillary nodal disease that becomes pathologically node-negative after chemotherapy given before surgery: regional nodal irradiation against no regional nodal irradiation, with the invasive breast cancer recurrence-free interval as the primary endpoint","sponsor":"NRG Oncology and the NSABP Foundation, funded by the National Institutes of Health","result":"Regional nodal irradiation after a complete nodal response to chemotherapy did not lengthen the invasive breast cancer recurrence-free interval (hazard ratio 0.88, 0.60 to 1.28, p=0.51); event-free estimates 92.7 against 91.8 percent.","yearReported":2025,"enrolled":1641,"enrolledBasis":"registered","enrolledNote":"1,641 patients were enrolled and 1,556 were included in the primary-event analysis; the ClinicalTrials.gov record NCT01872975 gives an estimated 1,636.","outcomes":[{"endpoint":"Invasive breast cancer recurrence-free interval","primary":true,"unit":"hazard ratio","arms":[{"name":"Regional nodal irradiation","n":772,"value":0.88,"note":"50 events; point estimate of survival free from primary endpoint events 92.7 percent"},{"name":"No regional nodal irradiation","n":784,"note":"59 events; point estimate 91.8 percent"}],"hr":0.88,"ci":[0.6,1.28],"p":"0.51","source":"https://doi.org/10.1056/NEJMoa2414859"}],"replication":"ATNEC is asking the same question about axillary surgery rather than radiotherapy and is still recruiting."},"route":"/trials/nsabp-b51/","neighbours":{"cancer":[{"id":"breast-cancer","kind":"cancer","name":"Breast cancer (all types)","route":"/cancers/breast-cancer/"},{"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":"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/"},{"id":"nsabp-foundation","kind":"company","name":"NSABP Foundation","route":"/companies/nsabp-foundation/"}],"term":[{"id":"neoadjuvant-versus-adjuvant-breast","kind":"term","name":"Drugs before or after the operation","route":"/terms/neoadjuvant-versus-adjuvant-breast/"},{"id":"pcr","kind":"term","name":"Pathologic complete response (pCR)","route":"/terms/pcr/"},{"id":"post-mastectomy-radiotherapy","kind":"term","name":"Radiotherapy after mastectomy","route":"/terms/post-mastectomy-radiotherapy/"},{"id":"targeted-axillary-dissection","kind":"term","name":"Targeted axillary dissection","route":"/terms/targeted-axillary-dissection/"}],"trial":[{"id":"acosog-z1071","kind":"trial","name":"ACOSOG Z1071 (Alliance)","route":"/trials/acosog-z1071/"},{"id":"atnec","kind":"trial","name":"ATNEC","route":"/trials/atnec/"},{"id":"eortc-22922","kind":"trial","name":"EORTC 22922/10925","route":"/trials/eortc-22922/"},{"id":"ma-20","kind":"trial","name":"NCIC MA.20","route":"/trials/ma-20/"},{"id":"supremo","kind":"trial","name":"SUPREMO (BIG 2-04)","route":"/trials/supremo/"}]}}