Survival with metastatic breast cancer based on initial presentation, de novo versus relapsed.

Purpose: We hypothesized different Overall Survival (OS) in metastatic breast cancer (MBC) after relapse vs de novo presentation.

Methods: We identified women in British Columbia with MBC diagnosed between 01/2001 and 12/2009. OS from MBC was calculated for relapsed vs de novo cohorts in 3 subgroups, based on hormone receptors (HR) and HER2 status. Age at MBC, disease-free interval (DFI), de novo vs relapsed, year of MBC diagnosis, and systemic treatment were entered into univariable and multivariable analyses.

Results: We identified 3645 pts with known HR of which 2796 had known HER2. Median follow-up was 91 months. Median OS was longer for de novo vs relapsed MBC: HR+/HER2- 34 versus 23 months (mos) (p < 0.0001), HR-/HER2- (TN) 11 versus 8 mos (p = 0.02), HER2+ 29 versus 15 mos (p < 0.0001). For TN disease, no variable independently discriminated a group with increased risk of death. For both the HR +/HER2- and the HER2 + groups, relapsed vs de novo status (HzR 1.4 [95% CI 1.2-1.5; p < 0.0001], and HzR 1.6 [95% CI 1.4-1.9; p < 0.0001], respectively) and age >50 (HzR 1.2 [95% CI 1.1-1.4; p = 0.001] and HzR 1.3 [95% CI 1.1-1.5; p = 0.01], respectively) were associated with increased risk of death on multivariable analysis.

Conclusion: These data provide information that may guide discussions about prognosis between physicians and patients with MBC. In addition, it highlights the importance of stratifying for initial stage at diagnosis in future MBC therapeutic trials.