Risk of heart disease following breast cancer: results from a population-based cohort study

BACKGROUND There is a rising concern about treatment-associated cardiotoxicities in breast cancer patients. OBJECTIVES This study aimed to determine the time- and treatment-specific incidence of arrhythmia, heart failure and ischemic heart disease in women diagnosed with breast cancer. METHODS A register-based matched cohort study was conducted including 8338 breast cancer patients diagnosed from 2001-2008 in the Stockholm-Gotland region and followed-up until 2017. Overall and time dependent risks of arrhythmia, ischemic heart disease and heart failure in breast cancer patients were assessed using flexible parametric models as compared to matched controls from general population. Treatment-specific effects were estimated in breast cancer patients using Cox model. RESULTS During a median follow-up of 10.8 years, the hazard ratios for arrhythmia, heart failure and ischemic heart disease, were 1.27 (95% CI = 1.18-1.37), 1.38 (95% CI = 1.23-1.55), and 0.93 (95% CI = 0.84-1.03), respectively. Time-dependent analyses revealed long-term increased risks of arrhythmia, and heart failure in breast cancer patients compared to matched controls. The risk of ischemic heart disease was only elevated in the first year after cancer diagnosis. Trastuzumab and anthracyclines were associated with increased risk of heart failure. Aromatase inhibitors, but not tamoxifen, were associated with risk of ischemic heart disease. No increased risk of heart disease was identified following loco-regional radiotherapy. CONCLUSIONS Administration of systemic adjuvant therapies appear to be associated with increased risks of heart disease. The risk estimates observed in this study may serve as reference to aid adjuvant therapy decision-making and patient counseling in oncology practices.