Androgen Deprivation Therapy for Prostate Cancer and the Risk of Venous Thromboembolism

BackgroundFew observational studies have investigated the association between androgen deprivation therapy (ADT) and venous thromboembolism (VTE) in patients with prostate cancer (PCa).ObjectiveTo determine whether the use of different types of ADT in patients with PCa is associated with an increased incidence of VTE.Design, setting, and participantsA population-based cohort study was conducted using the UK Clinical Practice Research Datalink linked to the Hospital Episode Statistics repository. The cohort consisted of men newly diagnosed with PCa between April 1, 1998, and March 31, 2014.Outcome measures and statistical analysisCox proportional hazards models with a time-varying exposure definition were used to estimate adjusted hazard ratios (HRs) with 95% confidence intervals (CIs) of patients hospitalized for VTE associated with current and past ADT use compared with nonuse. A secondary analysis was conducted to assess the risk with current use of specific types of ADT.Results and limitationsThe cohort included 21 729 patients, of whom 609 were hospitalized for VTE during follow-up. Current ADT use was associated with an 84% increased risk of VTE (incidence rates: 10.1 vs 4.8 per 1000 person-years; HR: 1.84; 95% CI, 1.50-2.26), whereas there was no association with past use (HR: 1.07; 95% CI, 0.81-1.42). In the secondary analysis, most types of ADT were associated with a high risk of VTE. Residual confounding is possible given the observational nature of the study.ConclusionsThe use of ADT was associated with an overall 84% increased risk of VTE, with the risk elevated for most ADT types.Patient summaryIn this study, we investigated whether androgen deprivation therapy was associated with the risk of blood clots in a cohort of patients with prostate cancer. We observed that the risk was nearly doubled in patients who used ADT compared with those who never used it. This treatment should be reserved for patients for whom the benefits outweigh the risks.