Breast cancer patients are twice as like to develop arterial thromboembolic events after diagnosis compared to cancer-free women

OBJECTIVES: To study occurrence of arterial thromboembolic events before and after breast cancer (BC) diagnosis compared to cancer-free controls as this information is lacking in published literature. METHODS: Women who had a first hospitalization for BC between 2002 and 2007 were selected from the PHARMO Record Linkage System, which includes drug use and hospitalization data of approximately 3 million residents in the The Netherlands. BC patients were matched 1:10 by age with cancerfree women, using the date of diagnosis as the index date for both BC patients and their controls. ATEE were defined as a myocardial infarction, ischemic stroke, unstable angina and transient ischemic attack requiring hospitalization and were assessed 12 months before and 12 months after the index date. RESULTS: The analysis included 11,473 BC patients, with a mean (±SD) age of 59 (±14) years. ATEE before the index date were twice as frequent among BC patients compared with cancer-free controls (Odds Ratio = 2.0[95%CI:1.6-2.6]), though prevalence was 10 days during the first 6 months of follow-up. CONCLUSIONS: In this population-based study, BC patients were twice as likely to develop ATEE compared to cancer-free controls, although the frequency of events was low. These results emphasize the need for careful observation of BC patients after diagnosis.