Cardiac toxicity associated with anthracycline-containing chemotherapy in older women with breast cancer

BACKGROUND: The purpose of this study was to determine the risk of chemotherapy-associated cardiac toxicity, including cardiac dysrhythmia, cardiomyopathy, congestive heart failure, ischemic heart disease, and conduction disorders among breast cancer patients with up to 16 years of follow-up. METHODS: The authors studied 19,478 women aged >65 diagnosed with breast cancer in 1991-1997 from 16 regions in the Surveillance, Epidemiology, and End Results program. Incidence density and cumulative incidence of cardiac toxicities were calculated, and the time-to-event (cardiac toxicity) analysis was conducted by using the Cox hazard regression model. RESULTS: The excess cumulative incidence of congestive heart failure in Year 10 among patients receiving anthracycline-containing chemotherapy compared with patients without chemotherapy was 4.7% (31.9% vs 27.2%). After adjusting for patient and tumor characteristics, patients receiving anthracyclines were 25% more likely to have congestive heart failure compared with those without chemotherapy (hazard ratio [HR], 1.25; 95% confidence interval [CI], 1.07-1.46). Those receiving other agents did not have a significantly elevated risk of developing congestive heart failure. The adjusted risk of cardiomyopathy was 2-fold higher in women who received anthracyclines (HR, 1.95; 95% CI, 1.44-2.62) and was 16% higher in those receiving other agents (HR, 1.16; 95% CI, 0.97-1.39) compared with those without chemotherapy. The increased risk for developing congestive heart failure, cardiomyopathy, and cardiac dysrhythmias in association with chemotherapy were similar after adjusting for hypertension and diabetes. The risk of ischemic heart disease and conduction disorders were not significantly different among the 3 groups. CONCLUSIONS: Anthracycline-containing chemotherapy regimens were associated with an increased risk of congestive heart failure, cardiomyopathy, and cardiac dysrhythmias, but not significantly associated with ischemic heart disease or conduction disorders.