Association between obesity and trastuzumab-related cardiac toxicity in elderly patients with breast cancer

PURPOSE: Trastuzumab can improve the prognosis for patients with breast cancer, but its related cardiac toxicity is concerning. This study aimed to identify the risk factors associated with trastuzumab-related cardiac toxicity in elderly patients with HER2-positive breast cancer. PATIENTS AND METHODS: A total of 133 elderly (≥ 65 years) patients who were diagnosed with breast cancer between June 1, 2007, and January 31, 2016, and received trastuzumab treatment were retrospectively reviewed. Cardiac events were defined as: (1) LVEF reduction of >10% from baseline echocardiography, (2) reduction of LVEF to <50%, and (3) signs and symptoms of heart failure as defined by the Common Terminology Criteria for Adverse Events (CTCAE) accompanied by a decrease in the LVEF. Univariate and multivariate regression analyses were used to determine the contribution of different clinical variables to trastuzumab-related cardiac events. RESULTS: The median age of the cohort was 71.0 years (range, 65–81 years). The median follow-up period for measurement of left ventricular ejection fraction was 11.0 months (range, 2–71 months). Fifteen patients (11.2%) experienced cardiac events during the follow-up. Multivariate regression analysis revealed that obesity (odd ratio[OR], 4.706; 95% CI, 1.984-10.147; P = 0.002) was a statistically significant risk factor associated with cardiac events. CONCLUSION: Obesity is an independent risk factor for trastuzumab-related cardiac toxicity in elderly patients with breast cancer, receiving trastuzumab. Further studies are needed to establish the independent predictive value of obesity on cardiotoxicity in these patients.