Additional radiotherapy to breast-conserving surgery is an optional treatment for de novo stage IV breast cancer: A population-based analysis

Abstract

Background: We aim to assess the value of locoregional treatment (LRT) including breast-conserving surgery (BCS), mastectomy (MAST), and radiotherapy (RT) in patients with de novo stage IV breast cancer. Methods: Patients with de novo stage IV breast cancer were retrospectively identified from the Surveillance, Epidemiology, and End Results database between 2004 and 2014. Kaplan-Meier analysis, log-rank tests, propensity score matching (PSM), and the multivariate Cox proportional model were used for statistical analysis. Results: A total of 5798 patients were identified including 849 (14.6%), 763 (13.2%), 2338 (40.3%), and 1848 (31.9%) who received BCS alone, BCS+RT, MAST alone, and MAST+RT, respectively. The proportions of receiving BCS decreased from 35.9% in 2004 to 26.2% in 2014 (p = 0.002), and the probability of patients receiving MAST increased from 64.1% in 2004 to 74.8% in 2014 (p = 0.002). Before PSM, there was a significant difference in breast cancer-specific survival (BCSS) among the treatment arms. Patients who received RT had better BCSS, the 5-year BCSS was 40.5%, 52.3%, 41.5%, and 47.7% in patients treated with BCS alone, BCS+RT, MAST alone, and MAST+RT, respectively (p < 0.001). In the PSM cohort, patients treated with BCS alone had lower 5-year BCSS compared to those treated with BCS+RT (43.9% and 52.1%, p = 0.002). However, there were comparable 5-year BCSS between BCS+RT and MAST alone groups (51.3% and 50.1%, p = 0.872), and BCS+RT and MAST+RT cohorts (51.5% and 55.7%, p = 0.333). Similar results were confirmed in multivariate analysis. Conclusions: Postoperative RT improves BCSS in patients with de novo stage IV breast cancer, and BCS+RT shows a non-inferior outcome compared to MAST+RT. BCS+RT may be the optimal local management of de novo stage IV breast cancer.