Radiotherapy after surgery has significant survival benefits for patients with triple-negative breast cancer

Objectives: The value of adjuvant radiotherapy for triple-negative breast cancer (TNBC) has been controversial recently. This study aims to clarify the influence of radiotherapy on the survival of TNBC patients after surgery based on a large population analysis.

Methods: The Surveillance, Epidemiology, and End Results (SEER) database was exploited to select eligible patients from 2010 to 2014. The categorical variables were examined by chi-square tests. Breast cancer-specific survival (BCSS) and overall survival (OS) were compared among patients who received or not received adjuvant radiotherapy after surgery by Kaplan-Meier method with log-rank test. Univariate and multivariate survival analysis of BCSS and OS were performed using the Cox proportional hazard model.

Results: Totally 22 802 patients were enrolled in this study, of which 10 905 patients received radiotherapy after surgery while 11 897 patients did not receive radiotherapy. Compared with those patients who did not receive radiotherapy, the radiation group had a larger proportion of tumor size <2.0 cm (45.8% vs 38.8%) and chemotherapy (82.5% vs 67.4%). The Kaplan-Meier plots displayed that patients in the radiation group had better survival than the no radiation group in both BCSS and OS (P < 0.001, respectively). In univariate Cox analysis of BCSS, age 40-60, married status, white and other race, chemotherapy, radiation, and surgery were associated with better survival (HR < 1, P < 0.05). Specifically, patients who received radiotherapy exhibited better BCSS (HR = 0.52, 95% CI = 0.48-0.57, P < 0.001). After adjusting for confounding factors by multivariable Cox regression analysis, receipt of radiotherapy was still associated with improved BCSS (HR = 0.79, 95% CI = 0.72-0.87, P < 0.001). Survival analysis of OS produced similar results. Generally, these data indicate that radiotherapy after surgery has significant survival benefits for the TNBC patients.

Conclusions: This study has confirmed the survival advantage of adjuvant radiotherapy for the TNBC patients. These findings may optimize the current individualized treatment decisions for this patient population.