Increasing survival of metastatic breast cancer through locoregional surgery

Surgery for the primary tumor in metastatic breast cancer is usually not recommended, assuming that local therapy provides no advantage. Recent reports suggest a survival improvement after locoregional treatment, but this is still controversial. We aimed to evaluate the effectiveness of locoregional treatment in primary metastatic breast cancer and to determine associated factors.

A retrospective analysis of 39 women with de-novo metastatic breast cancer at La Paz University Hospital, from January 2012 to June 2016, grouped by locoregional treatment (n=23) or not (n=16). Multivariate assessment of prognostic factors was performed using Cox regression analysis.

Mean tumor size was 6 cm. Eighteen patients (46.2%) had multifocal tumors, 29 (74.4%) multicentric and 10 (25.7%) bilateral breast cancer. Eighteen patients (46.2%) had an oligometastatic disease and 21 (53.8%) multiorgan metastatic disease. The average time from diagnosis to surgery was 7.7 months, without delay in the start of systemic treatment compared to the no-surgery group. The main surgical procedure was mastectomy in 18 (78.3%) patients. Half of the patients survived 48 months (95% CI: 39-57). In the multivariate analysis, we have not detailed differences in survival by age, chemotherapy, neoadjuvancy, number of systemic treatment lines, radiotherapy, and tumor histology or grade. However, surgery (HR=0.2; 95% CI: 0.07-0.57) and high tumor burden (HR=2.96, 95% CI: 1.23-7.13) have acted as a protective and a risk factor respectively.

Our cohort supports that locoregional treatment in selected patients with de-novo MBC significantly improved survival, so it might be considered in combination with systemic therapy.