Risk of thromboembolic diseases in men with prostate cancer: results from the population-based PCBaSe Sweden

BACKGROUND Cancer is associated with an increased risk of thromboembolic diseases, but data on the association between prostate cancer and thromboembolic diseases are scarce. We investigated the risk of thromboembolic disease in men with prostate cancer who were receiving endocrine treatment, curative treatment, or surveillance. METHODS We analysed data from PCBaSe Sweden, a database based on the National Prostate Cancer Register, which covers over 96% of prostate cancer cases in Sweden. Standardised incidence ratios (SIR) of deep-venous thrombosis (DVT), pulmonary embolism, and arterial embolism were calculated by comparing observed and expected (using the total Swedish male population) occurrences of thromboembolic disease, taking into account age, calendar-time, number of thromboembolic diseases, and time since previous thromboembolic disease. FINDINGS Between Jan 1, 1997, and Dec 31, 2007, 30 642 men received primary endocrine therapy, 26 432 curative treatment, and 19 526 surveillance. 1881 developed a thromboembolic disease. For men on endocrine therapy, risks for DVT (SIR 2.48, 95% CI 2.25-2.73) and pulmonary embolism (1.95, 1.81-2.15) were increased, although this was not the case for arterial embolism (1.00, 0.82-1.20). Similar patterns were seen for men who received curative treatment (DVT: 1.73, 1.47-2.01; pulmonary embolism: 2.03, 1.79-2.30; arterial embolism: 0.95, 0.69-1.27) and men who were on surveillance (DVT: 1.27, 1.08-1.47; pulmonary embolism: 1.57, 1.38-1.78; arterial embolism: 1.08, 0.87-1.33). Increased risks for thromboembolic disease were maintained when patients were stratified by age and tumour stage. INTERPRETATION All men with prostate cancer were at higher risk of thromboembolic diseases, with the highest risk for those on endocrine therapy. Our results indicate that prostate cancer itself, prostate cancer treatments, and selection mechanisms all contribute to increased risk of thromboembolic disease. Thromboembolic disease should be a concern when managing patients with prostate cancer. FUNDING Swedish Research Council, Stockholm Cancer Society, and Cancer Research UK.