Trastuzumab-induced cardiomyopathy: not as benign as it looks? A retrospective study.

BACKGROUND: One of the recent advances in the treatment of breast cancer is trastuzumab. However, a major side effect of this medication is cardiomyopathy. Our objective was to determine the incidence of trastuzumab-induced cardiomyopathy and the rate of discontinuation of trastuzumab in a clinical setting. METHODS AND
RESULTS: We retrospectively reviewed the records of all women treated with trastuzumab at the Moffitt Cancer Center between 2003 and 2007. Cardiomyopathy was defined as symptomatic heart failure or a decrease of ejection fraction by >or=10% from baseline or to <50%. Statistical analysis was done with Fisher exact test, t-test test, and Wilcoxon signed rank test. Cardiomyopathy developed in 52 of 156 (33.3%) of patients being treated with trastuzumab. In the adjuvant group, 23 (19.5%) of women permanently or temporarily discontinued therapy secondary to cardiomyopathy.
CONCLUSIONS: Cardiomyopathy is a common side effect of trastuzumab that leads to discontinuation of treatment in a significant proportion of patients. Further studies are indicated to establish the ways to predict, prevent, and treat cardiomyopathy to provide patients with maximal therapeutic benefit of trastuzumab.