Hypofractionation with simultaneous integrated boost after breast-conserving surgery: Long term results of two phase-II trials.

Purpose: To analyze long-term results of two multicenter prospective single-arm trials (ARO-2010-01 and ARO-2013-04) investigating adjuvant hypofractionated radiotherapy (HF) with simultaneous integrated boost (SIB) after breast-conserving surgery (BCS).

Methods: Eligible patients had histopathologically confirmed unifocal breast cancer planned for whole breast irradiation plus boost radiotherapy to the tumor bed. In both studies, a total dose of 40 Gy was applied to the whole breast and of 48 Gy to the tumor bed in 16 fractions of 2.