Increased risk of arterial thromboembolism in older men with breast cancer.

PURPOSE: Male breast cancer is a rare and understudied disease predominantly affecting men over age 60. Risk of arterial thromboembolic events (ATE) in men increases with age. We examined ATE risk following primary breast cancer diagnosis in elderly men.

METHODS: Men with primary breast cancer diagnoses from 2002 to 2011 were identified using the Surveillance, Epidemiology, and End Results (SEER)-Medicare-linked database. Cases were individually matched by age, sex, race, registry, and comorbidities with controls without cancer using SEER-Medicare's 5% noncancer sample. Medicare claims were used to identify ATE, defined as myocardial infarction or ischemic stroke. Cumulative incidence of ATE was calculated using competing risk methodology, with death considered a competing event. Cox proportional hazards analysis was used to compare rates of ATE among cases and controls.

RESULTS: Three months following primary breast cancer diagnosis, ATE risk in the cohort of 881 men was 80% higher than matched controls (hazard ratio 1.8; 95% confidence interval 1.0-3.2). Six months post-cancer diagnosis, 5.7% of cases had experienced ATE, whereas only 3.5% of controls had (HR 1.6; 95% CI 1.0-2.6). ATE risk remained elevated 12 months post-cancer diagnosis. Among cases, risk of death was threefold higher in men who developed ATE.

CONCLUSIONS: We provide population-based evidence that male breast cancer patients have a substantially elevated risk of ATE in the first year following a cancer diagnosis compared with matched controls. Care providers should consider this heightened risk when evaluating cardiovascular health in men with a recent breast cancer diagnosis.