A population-based, retrospective cohort study of 12,500 women diagnosed with incident, invasive breast cancer found that anthracycline and trastuzumab (Herceptin) were associated with increased risk of heart failure and/or cardiomyopathy. “Compared with women who received no chemotherapy, our hazard ratios suggest a fourfold increase in the risk of [heart failure/cardiomyopathy] among women who received trastuzumab alone and a sevenfold increase in the risk of [heart failure/cardiomyopathy] for those who received anthracycline plus trastuzumab,” the researchers reported in the Journal of the National Cancer Institute.
The women, who ranged in age from 22 to 99, had been enrolled at least 12 months before diagnosis in one of eight Cancer Research Network health systems. Most (46.5%) received no chemotherapy, 29.6% received anthracycline alone, 0.9% received trastuzumab alone, 3.5% received anthracycline plus trastuzumab, and 19.5% received other chemotherapy.
The cumulative incidence of heart failure/cardiomyopathy increased over 5 years, rising from 1.2% in year 1 to 4.3% at 5 years in women receiving anthracycline only, from 3.6% to 12.1% in women receiving trastuzumab only, from 6.2% to 20.1% in women receiving anthracycline plus trastuzumab, from 1.3% to 4.5%% in women receiving other chemotherapy, and from 0.9% to 3.1% in women who received no chemotherapy.
“The risk of incident [heart failure/cardiomyopathy] among all women was statistically significantly increased for anthracycline alone [adjusted HR = 1.40, 95% CI = 1.11–1.76], trastuzumab without anthracycline [HR = 4.12, 95% CI = 2.30–7.42], anthracycline plus trastuzumab [HR = 7.19, 95% CI = 5.00–10.35], and other chemotherapy [HR = 1.49, 95% CI = 1.25–1.77], compared with no chemotherapy,” the authors reported.
The women who received anthracycline alone or anthracycline plus trastuzumab were younger and had fewer comorbidities. “These results suggest substantial individualization of adjuvant chemotherapy administration by age and comorbidity in community practice,” the investigators noted.
“Consistent with previous studies, the majority of women 65 years or older in our population received no chemotherapy. Among older women who did receive chemotherapy, most received agents other than anthracycline or trastuzumab,” the researchers continued.
“This population-based observational study complements findings from clinical trials on cancer treatment safety,” the authors concluded. ■
Bowles EJ, et al: J Natl Cancer Inst 104:1293-1305, 2012.