Background: Although systemic therapy is the standard treatment for metastatic breast cancer, the value of locoregional treatment (LRT) of the primary tumor and its impact on survival is controversial. This study evaluates survival outcomes in patients with metastatic breast cancer after receiving LRT (surgery and/or radiation therapy) of the primary tumor.
Materials and methods: The National Cancer Database was used to identify 16,128 qualifying cases of metastatic breast cancer who received systemic therapy with or without LRT from 2004 to 2013. Treatment modality was divided into surgery (Sx), radiation therapy (RT), surgery followed by RT (Sx + RT), and no LRT. The median survival and 3-year actuarial survival rates (OS) were analyzed for each treatment group. On multivariate analyses, adjusted hazard ratios (HRs) with 95% confidence intervals (CIs) were computed using Cox regression modeling to adjust for patient and clinicopathologic characteristics.
Results: Overall, the median follow-up was 28.3 months, and the median survival for all patients was 37.2 months. With 9761 deaths reported, the estimated 3-year OS was 51.3%. The Sx + RT group (n = 2166) had the highest 3-year OS of 69.4%, followed by the Sx group (n = 4293) with 57.6%, the no LRT group (n = 8955) with 44.3%, and the RT group (n = 714) with 41.5% (P < .0001). On multivariate analysis, compared with the no LRT group, a decreased HR was noted in patients receiving Sx (adjusted HR, 0.68; 95% CI, 0.65-0.71; P < .0001) and Sx + RT (adjusted HR, 0.46; 95% CI, 0.43-0.49; P < .0001).
Conclusion: LRT, especially surgery followed by RT, in addition to systemic therapy, was associated with improved survival in patients with metastatic breast cancer.
Keywords: Local treatment; Overall survival; Radiation therapy; Stage IV breast cancer; Surgery.
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