Role of locoregional surgery in patients with de novo stage IV breast cancer: analysis of real-world data from China.

Stage IV breast cancer is metastatic breast cancer (MBC). Because real-world data are lacking in China, our research attempts to explore the effect of locoregional surgery on the prognosis of patients with MBC. A total of 987 patients from 10 hospitals and 2 databases in East China (2004-2018) were included in this study. Overall, 47% of patients underwent locoregional surgery, and 53% did not. Surgeons tended to perform surgery on patients with small tumours (T1/T2), positive hormone receptor (HR) markers, and metastatic sites confined to a single organ and non-visceral sites (bone only/others) (each p < 0.05). Kaplan-Meier survival curves and the log-rank test showed that median survival was longer for patients who had locoregional surgery than for those who did not (45.00 vs. 28.00 months; p < 0.001). Patients who underwent surgery after systemic treatment had better survival than those who underwent surgery immediately (p < 0.001). In most subgroups, overall survival (OS) was significantly longer in the surgery group than in the no-surgery group (each p < 0.05), except for brain metastases and triple negative breast cancer. Therefore, we concluded that locoregional surgery for the primary tumour in MBC patients was associated with a marked reduction in risk of dying except for patients with brain metastases or triple-negative subtype.