377P - Correlation of radiotherapy with the prognosis of elderly patients with hormone receptor-positive breast cancer according to immunohistochemical subtyping

Abstract

BackgroundThe present study examined the effect of radiotherapy on recurrence and survival in elderly patients with hormone-receptor-positive early breast cancer. MethodsA retrospective analysis of 327 patients aged ≥65 years with stage I-II, hormone receptor positive breast cancer who underwent breast conserving surgery and received endocrine therapy (ET) or radiotherapy plus endocrine therapy (ET+RT) was performed. Both groups were divided into luminal A type and luminal B type subgroups. Evaluation criteria were 5-year disease free survival (DFS), local relapse rate (LRR), overall survival (OS), and distant metastasis rate (DMR). ResultsThere were significant differences in 5-year DFS (HR 1.59, 95% CI 1.15–2.19, P=0.005) and LRR (HR 3.33, 95% CI 1.51–7.34, P=0.003), whereas there were no significant differences in OS and DMR between the two groups. In luminal A type, there was no significant difference in 5-year DFS, LRR, OS, and DMR between the ET group and the ET+RT group. In luminal B type, there were statistically significant differences in 5-year DFS (HR 2.188, 95% CI 1.37–3.49, P=0.001), LRR (HR 5.447, 95% CI 1.65–17.98, P=0.005), and OS (HR 1.752, 95% CI 1.01–3.054, P=0.048) between the two groups. In the ET group, there were significant differences between luminal A type and luminal B type in 5-year DFS (HR 1.841, 95% CI 1.23–2.75, P=0.003) and OS (HR 1.763, 95% CI 1.07–2.91, P=0.026). ConclusionsAfter breast conserving surgery, radiotherapy can reduce the LRR and improve the DFS and OS of luminal B type elderly patients, whereas luminal A type elderly patients do not benefit from radiotherapy. Without radiotherapy, luminal A type patients have better DFS and OS than luminal B type patients. Legal entity responsible for the studyThe author. FundingNational Natural Science Foundation of China (81672623). DisclosureThe author has declared no conflicts of interest.