In the last 5 years, mature follow-up analyses of randomized trials have been published offering fundamental insight into questions of dose and fractionation in breast cancer radiotherapy. Two landmark studies from the United Kingdom1 and Canada2 randomized women with early-stage breast cancer undergoing adjuvant breast irradiation to either conventionally fractionated radiotherapy over 5 weeks (50 Gy in 25 fractions) or hypofractionated radiotherapy over 3 to 4 weeks (40.0-42.5 Gy to the whole breast in 15-16 fractions). These trials showed comparable rates of local control and overall survival at 10 years.
Tanguturi SK, Bellon JR. Hypofractionation for Early-Stage Breast CancerNo More Excuses. JAMA Oncol. 2015;1(7):941-942. doi:10.1001/jamaoncol.2015.2605