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.