Prevention of Trastuzumab and Anthracycline-induced Cardiotoxicity Using Angiotensin-converting Enzyme Inhibitors or β-blockers in Older Adults With Breast Cancer.

Purpose: Although clinical trials have provided some data on the benefit of angiotensin-converting enzyme inhibitors (ACEIs) or beta-blockers (BBs) in patients with chemotherapy-induced cardiotoxicity, evidence of ACEIs/BBs on prevention of trastuzumab and/or anthracycline-induced cardiotoxicity outside trials is limited. Materials and Methods: A cohort study of 142,990 women (66 y and above) newly diagnosed with breast cancer from 2001 to 2009 was conducted using the Surveillance, Epidemiology, and End Results-Medicare-linked database. The ACEI/BB exposure was defined as filled prescription(s) before or after the initiation of trastuzumab/anthracyclines. The nonexposed group was defined as those who had never been prescribed ACEIs/BBs. Cumulative rates of cardiotoxicity and all-cause mortality were estimated and marginal structural Cox models were used to determine factors associated with cardiotoxicity and all-cause mortality adjusting for baseline covariates and use of chemotherapy. All statistical tests were 2 sided. Results: The final sample included 6542 women. Adjusted hazard ratio for cardiotoxicity and all-cause mortality for the ACEI/BB exposed group were 0.77 (95% confidence interval, 0.62-0.95) and 0.79 (95% confidence interval, 0.70-0.90) compared with the nonexposed group, respectively. Starting ACEIs/BBs <= 6 months after the initiation of trastuzumab/anthracyclines and having exposed duration >= 6 months were also associated with decreased risk of cardiotoxicity and all-cause mortality. Baseline characteristics, including age, non-Hispanic black, advanced cancer, region, comorbidity, preexisting cardiovascular conditions, lower socioeconomic status, and concomitant treatment were significantly associated with an elevated risk of all-cause mortality and/or cardiotoxicity (all P < 0.05). Conclusions: ACEIs/BBs show favorable effects on preventing cardiotoxicity and improving survival in female breast cancer patients undergoing trastuzumab/anthracycline treatment.