Breast Cancer Patients Are 30% More Likely To Develop Arterial Thromboembolic Events after Diagnosis Compared with Cancer-Free Women: Results from a Large Population-Based Study.
Authors: S. Shantakumar, M. van Herk-Sukel, J. Nelson, P. Kamphusisen, P. Abrahamson, R. Herings, F. Penning-van Beest
Journal: Cancer Research (2009)

Abstract Background: Population-based prevalence and incidence data of arterial thromboembolic events (ATEE) in breast cancer (BC) patients are lacking in the published literature.Objectives: The occurrence of ATEE before and after BC diagnosis was compared with cancer-free controls in a population-based setting.Methods: Women who had a first hospitalization for BC between 2002 and 2007 were selected from the PHARMO Record Linkage System (RLS), which includes drug use and hospitalization data from approximately 3 million residents in the Netherlands. BC patients were matched 1:10 by age with cancer-free controls, using the date of diagnosis as the index date for both BC patients and controls. ATEE were defined as a myocardial infarction, unstable angina, ischemic stroke, and transient ischemic attack requiring hospitalization and were assessed 12 mo before and after the index date.Results: The analysis included 11,437 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 (Table 1), though prevalence was &amp;lt; 1% in both groups. The incidence of developing ATEE in the 12-mo follow-up period was 6.2 per 1000 person years among patients and 3.8 among controls (Table 2). BC patients experienced 1.7 times higher risk of ATEE compared with controls. This risk was attenuated but remained statistically significant after adjusting for prior cardiovascular or thromboembolic event hospitalization and prior antithrombotic or cardiovascular drug use (HR=1.3 [95%CI: 1.0-1.7]). The increase in risk was slightly higher for cerebrovascular compared with coronary events. Independent risk factors for developing ATEE were age (≥ 65 vs &amp;lt; 65 years), prior use of antihypertensives or antidiabetic drugs, and total hospital stay &amp;gt; 10 days during the first 6 months of follow-up.Table 1. Prevalence of ATEE 12 mo Before BC Diagnosis BC Patients (N=11,473) %Cancer-free Patients (N=114,730) %Odds Ratio (95% CI)ATEE0.70.32.0 (1.6-2.6)Myocardial Infarction0.30.12.9 (1.9-4.2)Unstable Angina0.20.11.5 (0.9-2.3)Ischemic Stroke0.10.11.8 (1.0-3.1)Transcient Ischemic Attack0.10.02.1 (1.2-4.0) Table 2. Incidence of ATEE 12 mo After BC Diagnosis BC Patients (N=11,473) IR per 1000 PYCancer-free Controls (N=114,730) IR per 1000 PYHazard Ratio (95% CI)ATEE6.23.81.7 (1.3-2.2)Myocardial Infarction1.71.31.4 (0.8-2.2)Unstable Angina1.61.21.4 (0.8-2.2)Ischemic Stroke1.60.82.0 (1.2-3.3)Transcient Ischemic Attack1.40.82.5 (1.4-4.3) Conclusions: In this large population-based study, the occurrence of the arterial thromboembolic events was low. However, BC patients were at significantly higher risk of developing ATEE compared with cancer-free controls. These results emphasize the need for careful observation of BC patients after diagnosis. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 2050.