Bisphosphonate use and incident cardiovascular events among older breast cancer survivors

Background: Cardiovascular disease (CVD) is a leading cause of mortality in early-stage breast cancer survivors. Recent studies suggest that bisphosphonates may decrease CVD risk in older patients. Objective: This study sought to assess whether bisphosphonate use is associated with lower rates of incident CVD events among early-stage breast cancer survivors. Methods: Longitudinal, population-based cohort study was conducted by using data from the Surveillance, Epidemiology and End Results registry linked to Medicare claims. We identified women >65 years with no history of CVD who were diagnosed with stage 0-III primary breast cancer between 2007 and 2010. Our primary outcome was a composite of incident angina pectoris, myocardial infarction, atrial fibrillation/flutter, heart failure, or stroke within 36 months of cancer diagnosis. Bisphosphonate use was defined as the presence of >= 1 pharmacy claim from 6 months prior to cancer diagnosis to the incident CVD event. We used propensity scores to create a matched group of breast cancer survivors without bisphosphonate exposure to compare rates of incident CVD events. Results: A total of 2178 breast cancer survivors had >= 1 bisphosphonate prescription; the average length of bisphosphonate use was 15 months. Analyses of the matched data showed that 13.0% of bisphosphonate users and 23.4% of non-bisphosphonate users experienced an incident CVD event (p <0.0001) after breast cancer diagnosis. Bisphosphonate use was significantly associated with fewer incident CVD events (hazard ratio: 0.51, 95% confidence interval: 0.44 to 0.59). Conclusions: Bisphosphonate use is associated with lower incidence of CVD events among older early-stage breast cancer survivors. Future studies should prospectively evaluate whether bisphosphonate use can decrease CVD incidence. Published by Elsevier Ltd.