Abstract P2-14-28: Local surgery improves survival in patients with primary metastatic breast cancer: A population-based study

Abstract

Background The aim of this study was to assess the prognosis of breast cancer patients with distant metastasis after surgery of the primary tumor and provide new understanding of treatment for these patients. Methods We retrospectively analyzed 8922 primary metastatic breast cancer (PMBC) patients from Surveillance, Epidemiology, and End Results (SEER) Database. The patients' clinical and pathological characteristics were investigated. Overall survival (OS) and breast cancer-specific survival (BCSS) were calculated by Kaplan-Meier method. Independent risk factors associated with disease special mortality were identified by Cox regression analysis. Results A total of 8922 PMBC patients from SEER database were identified, while 1724 (19.3%) of them received surgery therapy (ST) and 7198 (80.1%) patients were identified as no surgery therapy group (NST). Patients' underwent ST had dramatically increased OS (P<0.001) and BCSS (P<0.001) compared with those in NST group. And the result figured out that the patients with 1 or 2 distant metastatic sites might benefit most from local surgery, while the prognosis of patients with 3 or more showed no significant difference (p= 0.073 for OS, p= 0.091 for BCSS). Furthermore, no differences were found in the survival rates between different surgical procedure groups (p= 0.886 for OS, p= 0.943 for BCSS). PMBC patients with ST tented to have increased OS (hazard ratio [HR] = 0.642; 95% confidence interval [CI], 0.583-0.707, p < 0.001) and BCSS (HR = 0.649; 95% CI, 0.587-0.718, p < 0.001), while age, grade, T stage, breast subtype, radiation, the number of metastatic site were also independent prognostic factors. Conclusions The current study demonstrated the survival benefit of ST in PMBC patients, especially those has 1 or 2 distant metastatic sites. Enlarged surgical range could not prolong survival. However, a large randomized clinical trial to validate the efficacy of ST in PMBC is essential in the future. Key words: primary metastatic breast cancer; SEER Database; survival; surgery Citation Format: Zhao Y, Sun H, Yang X, Zhao Y, Chen M, Jin W. Local surgery improves survival in patients with primary metastatic breast cancer: A population-based study [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-14-28.