Prognostic role of radiotherapy in low-risk elderly breast cancer patients after breast-conserving surgery: a cohort study.

Abstract

Previous research suggested that radiotherapy (RT) had a small absolute benefit in patients with low-risk breast cancer over the age of 65. To reduce the patient's treatment burden and cost, as well as the damage to normal tissue, this study sought to explore the prognostic role of RT after breast-conserving surgery (BCS) in elderly patients. Patients who were aged ≥65 years, stage T1N0M0, and estrogen receptor/progesterone receptor positive (ER+/PR+) were included in this study. Age, marital status, histology, race, grade, human epidermal growth factor receptor 2 (HER2), subtype, treatment method, and survival were also collected from the Surveillance, Epidemiology, and End Results (SEER) database from 2004 to 2015. We compared overall survival (OS) and breast cancer-specific survival (BCSS) before and after propensity score matching (PSM) in the patients who underwent BCS with or without RT. Kaplan-Meier method and Cox proportional hazards regression analyses were used in our study. The data of 3,623 patients were analyzed in this study. Among them, 2,851 (78.69%) patients had received RT. The multivariate analyses before PSM showed that RT resulted in better OS [hazard ratio (HR) 0.51, 95% confidence interval (CI): 0.42-0.62, P<0.001], and BCSS (HR 0.40, 95% CI: 0.27-0.58, P<0.001). The multivariate analyses after PSM (n=1,538) confirmed that patients who received RT (n=769) had a longer survival time than those who did not (n=769) (OS: HR 0.73, 95% CI: 0.57-0.95, P=0.018; and BCSS: HR 0.57, 95% CI: 0.35-0.93, P=0.025). The survival analysis showed that patients receiving RT had a better OS (P=0.028) and BCSS (P=0.016) than those who did not receive RT. However, there were no significant differences in patients' OS and BCSS with or without RT across the different age subgroups (P>0.05). In our study, patients who received RT had a longer survival time. However, the age subgroup analysis showed that RT did not have any survival benefit in elderly patients with T1N0M0 and ER+/PR+ breast cancer. Furthermore, at the age of 65-69 years, the P value for OS approached 0.05, which suggests that the decision to administer RT in this patient group should be made based on each patient's condition.