Estimated life years saved with trastuzumab in first-line HER2+ metastatic breast cancer from 1999 to 2013.

625 Background: Trastuzumab was approved in the United States (US) in September 1998 for the treatment of HER2+ metastatic breast cancer (MBC). This model estimates the total number of life years saved (LYS) in US women treated with trastuzumab over a 15-year period (1999-2013). Methods: Using US population estimates and cancer registry-based incidence data, we estimated the number of women with recurrent stage I-III or de novo stage IV HER2+ MBC by year, age, hormone receptor, and nodal status. Trastuzumab utilization was based on published studies of HER2 testing rates, true positive rates in the community, and treatment initiation rates. Survival was estimated by extrapolating survival data pooled across 5 trials and 2 observational studies separately for women treated with trastuzumab and with chemotherapy alone. Few studies reported survival in women with HER2+ MBC without trastuzumab (N=3). Sensitivity analyses were conducted by estimating overall survival from the initial phase 3 trial (67% of plac...