Trastuzumab-Induced Cardiomyopathy: Not as Benign as it Looks? A Retrospective Study

BackgroundOne 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 ResultsWe 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 ≥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.ConclusionsCardiomyopathy 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.