Radiation therapy and overall survival in male breast cancer: a multicenter analysis of 302 patients.

AIM: This multicenter study aimed to assess the efficacy and the prognostic role of adjuvant radiation therapy and other factors in a cohort of male breast cancer patients (MaBC) treated in 10 Italian centers within the Clinical Oncology Breast Cancer Group. METHODS: This retrospective study included patients diagnosed with MaBC between 2005 and 2023. Demographic, clinical, tumor, and treatment data were retrieved from medical records. Information on treatment-related acute and late adverse events was also collected. Disease-free survival (DFS) was calculated from surgery to recurrence or last follow-up visit, overall survival (OS) from diagnosis to death or last follow-up visit. RESULTS: Overall, 302 patients were included (median age 69). Most were diagnosed with stage I-IIIa (75%; vs 25% stage IIIb-IV), invasive ductal carcinoma (88%) and luminal-like tumors (88%). Nearly all patients underwent mastectomy (96%), 31% received adjuvant chemotherapy, 83% endocrine therapy (mainly tamoxifen), and 33% radiation therapy. At a median follow-up of 79 months, DFS and OS were significantly associated, among others, with stage (p < 0.05). In stage IIIb-IV patients, omission of radiation therapy was associated with higher recurrence risk (hazard ratio, HR = 18.8, p < 0.001) and worse OS (HR = 6.45, p < 0.001). Acute radiation therapy-related adverse events occurred in 28% of patients, mostly graded 1-2, but no severe late toxicity was observed. CONCLUSIONS: This large retrospective cohort study showed that MaBC patients treated with multi-modality therapies achieved favorable outcomes. Specifically, radiation therapy significantly improved survival in advanced stages with low incidence of late adverse events further supporting its role in daily clinical practice.