Comparative effectiveness of radiotherapy for early-stage hormone receptor-positive breast cancer in elderly women using real-world data

Background: Radiotherapy is the recommended treatment after breast-conserving surgery (BCS) for early-stage breast cancer (BC). However, there is no clear evidence whether radiotherapy after BCS improves the survival of elderly women diagnosed with early-stage hormone receptor-positive (HR+) BC. The aim of this study was to investigate the survival benefit associated with radiotherapy plus hormonal therapy vs hormonal therapy alone after BCS for early-stage HR+ BC patients. Methods: Using the Surveillance, Epidemiology, and End Results linked with Medicare data, we identified elderly (65 years and older) women diagnosed with early-stage HR+ BC (2006-2011) who received hormonal therapy with or without radiotherapy after BCS. A log-rank test, Cox proportional hazards models, and propensity score matching were used to estimate the overall survival (OS) benefit associated with radiotherapy after BCS. Results: Of the 5688 patients, there were 303 deaths from any cause. One hundred and eighty-five (61%) of these deaths occurred in the hormonal therapy group, and 118 (39%) deaths occurred in the radiotherapy plus hormonal therapy group. The mean survival time in the radiotherapy plus hormonal therapy group was 5.32 ± 1.86 years compared with 4.92 ± 1.86 years in the hormonal therapy group. Based on the adjusted and propensity score matching analysis, patients in the adjuvant radiotherapy group had a lower risk of death compared with those who did not receive radiotherapy. Radiotherapy plus hormonal therapy decreased the risk of death by 32%. The effect estimates were similar in the adjusted and matched cohorts. Conclusions: Radiotherapy plus hormonal therapy resulted in a significant improvement in the OS of elderly women diagnosed with HR+ BC.