Locoregional Therapy in De novo Metastatic Breast Cancer: A Retrospective Cohort Study

Objective: Whether locoregional therapy (LRT) should be performed in patients with de novo metastatic breast cancer (dnMBC) has been debated. Here we report the survival outcomes of LRT in patients with dnMBC, focusing on the association of surgical timings and surgical margins with survival in this patient population. Methods: The retrospective study included patients with dnMBC in our hospital, between March 1, 2007 and December 31, 2017. Overall survival (OS) was evaluated by means of a stratified log-rank test and summarized with the use of Kaplan–Meier methods. Results: A total of 153 patients were included, of whom 87 underwent LRT and 66 systemic therapy alone (STA). LRT showed a significant OS benefit over STA (HR, 0.62; 95% CI, 0.39 to 0.99; P = .043). The OS of LRT group and STA group were 39 months (95% CI, 33.6 to 44.4 months) and 24.6 months (95% CI, 20.6 to 28.6 months), respectively. The benefit was consistent across most subgroups. The OS of patients undergoing surgery was better than that of patients without surgery (HR, 0.58; 95% CI, 0.35 to 0.94; P = .0001), and there was difference in survival improvement at different surgical timings (surgery before chemotherapy, during chemotherapy, and after chemotherapy) (P = .0001). The survival benefit of surgery after chemotherapy was significantly greater than that of the other 2 options (HR, 0.77; 95% CI, 0.63 to 0.94). Moreover, compared with patients with positive margins, the OS of patients with negative margins was significantly improved (HR, 0.22; 95% CI, 0.13 to 0.37; P < .001). Conclusions: Our results suggest that LRT is associated with improved OS in women with dnMBC, and patients who had surgery after systemic chemotherapy with negative surgical margins, are expected to benefit more.