Survival in patients with non-metastatic breast cancer treated with adjuvant trastuzumab in clinical practice.

The NSABP Trial B-31 and NCCTG Trial N9831 (B-31/N9831 trials, Romond et al. in N Engl J Med 353:1673-84, 2005. doi:10.1056/NEJMoa052122; Perez et al. in J Clin Oncol 32:3744-52, 2014. doi:10.1200/JCO. 2014.55.5730) established the efficacy of adjuvant trastuzumab for patients with HER2-positive early stage breast cancer. We aimed to estimate the overall survival (OS) and relapse-free survival (RFS) of HER2-positive non-metastatic breast cancer patients treated with adjuvant trastuzumab in a clinical practice setting in the United States.

Adult women initiating adjuvant trastuzumab within 1 year of breast cancer surgery were identified in the health claims database of the US Department of Defense (01/2003-12/2012). OS and RFS unadjusted rates at 4 and 6 years after the first trastuzumab treatment following the breast cancer diagnosis were estimated from Kaplan-Meier analyses.

The study sample included 3188 women followed for a median of 3.3 years after trastuzumab initiation and treated continuously with trastuzumab for a median of 12 months. The OS rates (95 % confidence intervals) at 4 and 6 years were 90.0 % (88.6-91.2) and 87.1 (85.3-88.6), respectively. The corresponding RFS rates were 75.8 % (74.0-77.5) and 72.7 (70.7-74.7), respectively. The OS and RFS rates at 6 years reported in the B-31/N9831 trials were 89.8 and 81.4 %, respectively.

OS rates estimated in this study were in range with those estimated in the B-31/N9831 trials, while RFS rates were lower. However, patients in the B-31/N9831 trials were younger and possibly had fewer comorbidities than patients in the current study; these differences were not adjusted for in the crude OS and RFS analyses.

SpringerPlus. 2016 Mar 31*** epublish ***

Christopher M Gallagher, Kenneth More, Anthony Masaquel, Tripthi Kamath, Annie Guerin, Raluca Ionescu-Ittu, Roy Nitulescu, Marjolaine Gauthier-Loiselle, Nicholas Sicignano, Elizabeth Butts, Eric Q Wu, Brian Barnett

Washington Cancer Institute, MedStar Washington Hospital Center, 110 Irving Street, NW, Room C-2149, Washington, DC 20010-2975 USA., Virginia Oncology Associates, Virginia Beach, VA USA., Genentech, Inc., South San Francisco, CA USA., Analysis Group, Inc., Montreal, QC Canada., Health ResearchTx, Trevose, VA USA., Navy and Marine Corps Public Health Center, Portsmouth, VA USA., Analysis Group, Inc., Boston, MA USA.