Ten-Year Outcomes of Hypofractionated Postmastectomy Radiation Therapy of 26 Gy in 6 Fractions

To investigate the efficacy and long-term side effects of hypofractionated postmastectomy radiation therapy (HFRT-PM) of 26 Gy in 6 fractions over 5 weeks.

We retrospectively reviewed characteristics and outcomes of patients with stage I to III breast cancer treated with HFRT-PM between 2000 and 2009. Treatment provided 4 fractions of 4 Gy (days 1, 3, 15, 17) and then 2 fractions of 5 Gy (days 29 and 31) over 5 weeks. The treatment techniques were applied by using 3-dimensional conformal radiation therapy of the chest wall with regional nodal volume if required.

We identified 454 patients with a median follow-up of 10.6 years (range, 0.5-22.9). Regional nodal irradiation was done in 84.1% of patients. At 10 years, the cumulative incidence of locoregional relapse was 15.1%. In multivariate analysis, regional lymph node involvement (≥4 nodes) was associated with worse locoregional control (hazard ratio, 1.68; 95% confidence interval, 1.06-2.67; P = .03) and overall survival (hazard ratio, 2.16; 95% confidence interval, 1.59-2.95; P < .001). The toxicities were acceptable. The incidence of cardiac disorders (3.3%), and symptomatic lung fibrosis (1.5%) was low during follow-up. At 10 years, the cumulative rate of arm lymphedema was 9.5% and considered severe in 20 patients (4.4%).

The long-term results of this study show that HFRT-PM of 26 Gy in 6 fractions over 5 weeks seems safe, but locoregional recurrence seems slightly higher than that observed in the literature, highlighting the need for long-term follow-up and for randomized trials for hypofractionated radiation therapy postmastectomy.