The Role of Adjuvant Radiotherapy in Low-Risk Elderly Male Breast Cancer: Is Omission Justified?

Background The aim of our study is to evaluate the net survival benefit of adjuvant radiotherapy following breast-conserving surgery (BCS) in elderly male patients with early-stage, low-risk breast cancer (node-negative, hormone receptor-positive [HR+]) and to assess whether omitting radiotherapy might be a viable option based on observed survival outcomes. Methods We conducted a retrospective cohort study using data from SEER-17 registries (2000–2021), identifying 9,695 male breast cancer (MBC) patients. After applying inclusion criteria and PSM, a total of 360 patients were included. Early-stage, low-risk patients were categorized into radiotherapy (RT) and non-radiotherapy (NRT) groups. A 1:3 nearest neighbor propensity score matching (PSM; caliper = 0.05) was used to adjust for confounders. Estimate the net survival benefit of RT by using overall survival (OS), relative survival (RS), standardized mortality ratio (SMR), and transformed Cox regression, while controlling for background mortality. Results In early-stage, low-risk MBC patients underwent BCS, RT did not confer a significant survival benifit compared to those who omitted RT. After PSM adjustment, the 15-year OS, RS, and SMR for the RT group were 31.8%, 1.05, and 2.14, respectively, with no statistically significant differences observed when compared to the NRT group (34.1%, 1.03, and 2.25; p = 0.36, 0.35, and 0.81, respectively). Furthermore, the cumulative incidence of breast cancer-related death (BCRD) and non-BCRD did not differ significantly between the RT and NRT groups. The 15-year cumulative incidences of BCRD and non-BCRD were 7.0% and 61.2% in the RT group, and 12.4% and 53.5% in the NRT group (p = 0.06 and 0.75, respectively). Additionally, compared to the NRT group, the RT group demonstrated a lower risk for both OS and RS within the first 10 years following diagnosis, although this survival benefits gradually diminished over time. Conclusions In MBC patients over 65 with T _1 − 2 N ₀ M ₀ , hormone receptor-positive tumors, radiotherapy showed no significant improvement in overall, disease-specific, or net survival. Therefore, omitting radiotherapy may be justified for early-stage, low-risk patients, aligning treatment with individualized risk assessments.