Surgical removal of the primary tumor increases overall survival in patients with metastatic breast cancer: analysis of the 1988-2003 SEER data.

Primary treatments for stage IV breast cancer are chemotherapy and radiation, with surgery usually reserved for tumor-related complications. We sought to determine whether surgical removal of the primary tumor provides a survival advantage for women with metastatic breast cancer. We conducted a retrospective, population-based cohort study by using the 1988-2003 Surveillance, Epidemiology, and End Results (SEER) program data. By use of multivariate Cox regression models, overall survival in women with stage IV disease was compared between women who underwent surgical excision of their breast tumor with women who did not, controlling for potential confounding demographic, tumor- and treatment-related variables, and propensity scores (accounting for variables associated with the likelihood of having surgery). Of 9734 SEER patients with stage IV breast cancer, 47% underwent breast cancer surgery and 53% did not. Median survival was longer for women who had surgery than for women who did not, both among women who were alive at the end of the study period (36.00 vs. 21.00 months; P < .001) and among women who had died during follow-up (18.00 vs. 7.00 months; P < .001). After controlling for potential confounding variables and propensity scores, patients who underwent surgery were less likely to die during the study period compared with women who did not undergo surgery (adjusted hazard ratio, .63, 95% confidence interval, .60-.66). Analysis of the 1988-2003 SEER data indicated that extirpation of the primary breast tumor in patients with stage IV disease was associated with a marked reduction in risk of dying after controlling for variables associated with survival.