The effect of adjuvant radiotherapy after breast-conserving surgery in elderly women with T1-2N0 estrogen receptor-negative breast cancer

PURPOSE: To evaluate whether adjuvant radiotherapy (RT) following breast-conserving surgery (BCS) results in better survival among women ≥ 70 years with T1-2N0 estrogen receptor (ER)-negative breast cancer. METHODS: In this retrospective cohort study, we included patients who met the inclusion criteria between 2010 and 2015 from the Surveillance, Epidemiology, and End Results (SEER) program. Univariate and Multivariate Cox proportional analysis were used to identify the risk factors for overall survival (OS) and breast cancer-specific survival (BCSS). Kaplan-Meier survival analysis was used to compare the prognosis of patients with or without adjuvant RT. Propensity score matching (PSM) was applied to perform a 1:1 matched case-control analysis. RESULTS: A total of 4201 women were included in this study, with a median follow-up time of 64 months (range: 0–107 months). Of these patients, 2811 (66.9%) received adjuvant RT, while 1390 (33.1%) did not. Patients who did not receive adjuvant RT were more likely to be aged ≥ 80 years old, have a single marital status, larger tumors, and HER2-positive status (p < 0.05). Multivariate Cox proportional analysis indicated that receiving adjuvant RT was an independent factor associated with better OS and BCSS before and after PSM (P < 0.001). The survival curves before and after PSM showed that patients achieved an improved OS and BCSS from adjuvant RT (P < 0.005). In the subgroup analysis, there was no survival benefit trend from adjuvant RT in patients who were ≥ 80 years, or those with T1mic+T1a, T1b tumors. CONCLUSIONS: The use of RT following BCS in older women with T1-2N0 ER-negative breast cancer is associated with improve OS and BCSS. However, the potential benefit may be relatively limited for patients ≥ 80 years, or those with T1mic+T1a, T1b tumors.