Locoregional surgical treatment improves the prognosis in primary metastatic breast cancer patients with a single distant metastasis except for brain metastasis.

BACKGROUND: We aimed to validate the clinical significance of locoregional surgery in improving the prognosis of primary metastatic breast cancer (pMBC). METHODS: We conducted a population-based retrospective study by analyzing clinical data obtained from the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) database. Stratification analysis was employed to assess the effect of breast surgery on breast cancer-specific survival and overall survival. Then propensity score matching and COX regression models were employed to evaluate the survival advantages of breast surgery, if any in patients with pMBC. RESULTS: The median BCSS and OS in the surgery group were almost twice of that in the group without surgery. Breast surgery provided a survival advantage for patients with a single metastasis in the bone, liver or lung, but not in the brain. We found that axillary lymph node dissection performed in combination with specific breast surgical procedures did not result in a significant improvement in survival. Additionally, when combined with radiotherapy and/or chemotherapy, surgery significantly improved the survival and was not influenced by the molecular subtype and tumor size. Finally, using COX regression models before and after propensity score matching, breast surgery was found to reduce the risk of mortality in patients with MBC by more than 40%. CONCLUSIONS: The effect of locoregional surgery has been underestimated in pMBC patients. Surgical procedures should be seriously considered when planning combination treatments for pMBC patients with a single metastasis except for brain metastasis.