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

ABSTRACT

Purpose: 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. Materials & Methods: We retrospectively reviewed characteristics and outcomes of patients with stage I-III breast cancer treated with HFRT-PM between 2000–2009. Treatment provided four fractions of 4 Gy (day (d)1, d3, d15, d17) then two fractions of 5 Gy (d29, d31) over 5 weeks. The treatment techniques were applied by using 3D conformal radiotherapy of chest wall with regional nodal volume if required. Results: 454 patients were identified, with a median follow-up of 10.6 years (range 0.5-22.9). Regional nodal irradiation was made in 84.1 % of patients. At 10 years, the cumulative incidence of locoregional relapse was 15.1 %. In multivariate analysis, regional lymph nodes involvement (≥ 4 nodes) was associated with worse locoregional control (HR 1.68; [95% CI 1.06–2.67], p = 0.03) and overall survival (HR 2.16; [95% CI 1.59–2.95], p < 0.001). 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 %). Conclusion: The long-term results of this study show that HFRT-PM of 26 Gy in 6 fractions over 5 weeks seems safes but locoregional recurrence seems slightly higher than those observed in the literature, highlighting that long-term follow-up is needed and the need of randomized trials for hypofractionated radiotherapy therapy in postmastectomy situation.