Physical activity and incident cardiovascular disease in breast cancer survivors: the Pathways Study.

Background: Breast cancer survivors experience higher rates of cardiovascular disease (CVD) than women without breast cancer, due in part to cardiotoxic cancer treatments and shared lifestyle risk factors. Physical activity is associated with lower mortality risk in breast cancer survivors, but associations with CVD have not been examined in detail.

Methods: The Pathways Study is a prospective cohort study of 4504 women diagnosed with invasive breast cancer between 2005 and 2013. At enrollment, women self-reported their physical activities during the previous 6 months, which were dichotomized as meeting the Centers for Disease Control and Prevention's Physical Activity Guidelines for Americans (≥150 minutes of moderate-intensity or ≥75 minutes of vigorous-intensity activity per week) vs not. Incident CVD events (heart failure, cardiomyopathy, cardiac arrest, ischemic heart disease, stroke) occurring between enrollment and December 2021 were identified from electronic health records. Covariate-adjusted, competing-risks Cox regression models estimated associations between meeting physical activity guidelines and CVD risk.

Results: Compared with women who did not meet physical activity guidelines at their diagnosis, those who did had a 25% lower risk of CVD (HR = 0.75, 95% CI = 0.60 to 0.94). Among the individual CVD outcomes, meeting physical activity guidelines was protective against incident cardiomyopathy (hazard ratio [HR] = 0.54, 95% CI = 0.31 to 0.95), heart failure (HR = 0.66, 95% CI = 0.50 to 0.87), and cardiac arrest (HR = 0.68, 95% CI = 0.49 to 0.99).

Conclusions: Meeting physical activity guidelines at breast cancer diagnosis was associated with lower risk of CVD after diagnosis. Studies investigating changes in physical activity after a breast cancer diagnosis and CVD risk are warranted.