Concurrent boost (SIB) during whole-breast RT matches sequential boost control in high-risk early breast cancer, shortening treatment time

NRG/RTOG 1005 tested whether delivering the lumpectomy-cavity boost concurrently (a simultaneous integrated boost using 3D-CRT/IMRT) could maintain local control versus the standard sequential boost delivered after whole-breast irradiation (WBI). In this Phase III trial of higher-risk patients after lumpectomy/axillary surgery (n=2,255; sequential n=1,118 vs concurrent n=1,137; enrolled 2011-2014), 5- and 7-year ipsilateral breast recurrence (IBR) were 2.1% and 2.2% with sequential boost vs 1.9% and 2.6% with concurrent boost; noninferiority was met (HR 1.31, 90% CI 0.84-2.04; p=0.037), with no detected differences in adverse events, cosmesis, DFS, or OS—while reducing overall treatment duration versus the common sequential-boost approach (typically adds ~1-2 weeks).