Hypofractionated Vs Conventional Fractionated Radiotherapy After Breast Conserving Surgery

Eligible patients after breast conserving surgery will be randomized 1:1 into hypofractionated radiotherapy (HF-RT) group or conventionally fractionated radiotherapy (CF-RT) group. Patients in HF-RT group will receive 40 Gy/15 fractions irradiation to the whole breast with/without regional lymphnodes within 3 weeks and the tumor bed is boosted to 48 Gy/15 fractions simutaneously. Patients in CF-RT group will receive 50 Gy/ 25 fractions irradiation to whole breast with/without regional lymphnodes within 5 weeks and the tumor bed is boosted to 60 Gy/30 fractions sequentially. The primary endpoint is loco-regional recurrence. Other cancer related events and acute/late radiation morbidities will also be evaluated. The patients will be followed for 10 years. It is hypothesized that hypofractionated radiotherapy is non inferior to conventional fractionated radiotherapy in terms of tumor loco-regional control for patients after breast conserving surgery.