Background: The median survival for patients (pts) receiving trastuzumab (T) in the metastatic setting is approximately 3 years. There are limited data on real world use and outcomes in T treated pts who live longer than 3 years. The objective of this study was to identify and characterize pts with HER2+ MBC who initiated treatment with T (alone or in combination) in a community setting and to determine their treatment patterns and outcomes, including duration of treatment, overall survival (OS) and time to permanent discontinuation of T. Methods: A retrospective observational study was performed using the IKnowMed electronic medical record (EMR) used by the US Oncology Network with the primary time period of 2007 through Dec. 2012. Eligible pts had at least 2 visits at practice locations with full EMR capability. Pts on T when the EMR was implemented had chart review to determine the dates of diagnosis and start of T treatment. Results: The study population included 1856 women with HER2+ MBC who started T (alone or in combination with chemotherapy or hormonal therapy); 873 presented with MBC and 983 developed recurrence following diagnosis of early-stage disease. The median age was 58, range 23 to 96, 59% had ER+ cancer, 64% were postmenopausal and 35% had multiple sites of disease at presentation. Median OS for the entire group was 40.9 months and the median time to permanent discontinuation of T was slightly less, at 39.9 months. Interestingly, the median OS and duration of T use were similar in the recurrent MBC population and in the population who presented with de novo MBC. The proportion of pts receiving T and OS by year are presented (Table). Thirty-two percent of pts are still alive at 6 years, with 17% continuing to receive T.

Outcomes of 1856 Patients Treated with Trastuzumab

Year 1 3 5 6 
Pts still receiving T (%) 82% 53% 27% 17% 
OS (%) 84% 54% 36% 32% 
Year 1 3 5 6 
Pts still receiving T (%) 82% 53% 27% 17% 
OS (%) 84% 54% 36% 32% 

Ongoing analysis will evaluate whether there are pt and treatment characteristics that may predict for longer term OS. Conclusions: Using an EMR database we identified 1856 women with HER2+ MBC who initiated treatment with T (alone or in combination) with one third still alive at 5 years and 27% still on T. Future research that focuses on understanding the characteristics of this population can potentially improve care for women with HER2+ MBC with T and newer anti-HER2 agents.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-16-09.