Is the Proportion of Patients Diagnosed with Synchronous Stage IV Breast Cancer Who Survive More than Two Years Increasing over Time?

Background: Studies have shown a moderate increase in survival over time among patients with stage IV breast cancer. Median survival is approximately 2 years. The aim of this study was to evaluate trends over time in survival of >2 years of patients with synchronous stage IV disease. Methods: Using the SEER (Surveillance, Epidemiology and End Results) registry, we identified patients with synchronous stage IV breast cancer diagnosed between 1990 and 2007. Patients were divided into 3 groups according to the year of diagnosis (1990-1995, 1996-2000, and 2001-2007). The probability of survival of >2 years was computed within each group of diagnosis years. A multivariate logistic regression model was then fit to determine the association between year of diagnosis and probability of surviving >2 years after adjusting for important prognostic factors. Results: 22,601 patients were identified, of whom 9,435 (41.7%) had an overall survival of >2 years. The probability of breast cancer-specific survival (BCSS) of >2 years was 40.1, 44, and 48.1% among patients diagnosed in the periods 1990-1995, 1996-2000, and 2001-2007, respectively (p < 0.001). In the multivariate model, the probability of BCSS of >2 years increased with the more recent year of diagnosis (OR 1.058, 95% CI 1.046-1.069, p < 0.001). Other factors significantly associated with an increased probability of surviving >2 years included surgery of the primary tumor, lower grade, younger age, hormone receptor-positive disease, and noninflammatory disease. Conclusion: Our results indicate that among the patients with synchronous stage IV breast cancer, the probability of BCSS of >2 years in the US has increased over time. Attributable factors may be the increasing number of efficacious agents and improved palliative care services over time.