Background: Surgery for the primary breast tumour is usually not recommended in metastatic breast cancer (MBC); however, some reports have suggested a benefit of locoregional treatment. We designed this study to evaluate the efficacy of locoregional surgery in MBC.
Methods: Data for patients diagnosed with MBC at Samsung Medical Center between 1995 and 2011 were retrospectively collected. We compared the survival benefit of all treatment modalities using Cox regression analysis. Subgroup analyses based on number of metastases were performed to delineate the indication for each treatment.
Results: Among 262 patients, 40 (15.3%) underwent surgery. Other treatments included chemotherapy (n = 213, 81.3%), radiotherapy (n = 138, 52.7%), hormone therapy (n = 118, 45.0%) and HER2/neu receptor (HER2)-targeted therapy (n = 37, 14.1%). Cox regression analysis showed that surgery (hazard ratios (HR) = 0.51, P < 0.01), hormone therapy (HR = 0.31, P < 0.01) and HER2-targeted therapy (HR = 0.33, P < 0.01) were associated with improved survival, whereas presence of three or more metastatic organs (HR = 1.62, P = 0.03) was associated with poor survival. In patients with metastasis to a single organ, surgery (HR = 0.43, P < 0.01), chemotherapy (HR = 0.62, P = 0.05), hormone therapy (HR = 0.39, P < 0.01) and HER2-targeted therapy (HR = 0.39, P = 0.02) had a survival benefit. Furthermore, for patients with bone-only metastasis, surgery (HR = 0.37, P = 0.02), chemotherapy (HR = 0.42, P < 0.01), hormone therapy (HR = 0.22, P < 0.01) and HER2-targeted therapy (HR = 0.09, P = 0.02) showed a survival benefit. However, only hormone therapy and HER2-targeted therapy had a survival benefit in MBC with metastasis to multiple organs.
Conclusion: Surgical control of the primary breast tumour should be considered as a locoregional therapy in combination with systemic therapy in MBC with metastasis to a single organ, especially bone-only metastasis.