Abstract
BACKGROUND: The purpose of this observational study was to report clinical outcomes in a consecutive series of elderly and/or comorbid patients with early breast cancer treated with once-weekly postoperative whole-breast radiation therapy (WBRT) after breast-conserving surgery (BCS). PATIENTS AND METHODS: A total 334 patients underwent WBRT between 2007 and 2019. Patients received a dose per fraction of 5.7 Gy (total dose 28.5 Gy) or 6.5 Gy (total dose 32.5 Gy) in 5 weekly fractions. Clinical endpoints included local control (LC), disease-free survival (DFS), cancer-specific survival (CSS), overall survival (OS), acute and late complications, and cosmesis. RESULTS: Median follow-up was 60 months (range: 11-152 months). Most patients had pT1 tumours (52.1 %), pN0 (56.9 %) and invasive ductal tumours (79 %). Three-year locoregional control was 98.7 %, and three-year overall survival, disease-free survival and cause-specific survival were 90 %, 94.4 % and 94.1 %, respectively. Acute dermatitis was Grade 0 in 34 (10.2 %), Grade 1 in 203 (60.8 %), Grade 2 in 81 (24.3 %), and Grade 3 in 15 (4.5 %) patients. Late complications consisted of fibrosis: Grade 0 in 251 (75.1 %), Grade 1 in 58 (17.4 %), Grade 2 in 18 (5.4 %), and Grade 3 in 6 (1.8 %); all Grade 3 cases occurred in patients treated with 6.5 Gy per fraction. Lymphedema was observed in 31 (9.3 %) patients. CONCLUSION: Once-weekly hypofractionated WBRT (28.5-32.5 Gy in 5 fractions) was feasible and effective, with 99.7 % treatment compliance. The 28.5 Gy regimen was associated with significantly less fibrosis and may be preferable, particularly for elderly and/or comorbid patients.