Entacapone did not Increase Prostate Cancer Risk or Mortality in Patients with Parkinson's Disease

The association between Parkinson’s disease (PD) and prostate cancer (PCA) is under discussion. We investigated whether exposure to entacapone increases risk of PCA by comparing PCA incidence and mortality rates in PD patients treated with levodopa and dopa decarboxylase inhibitors (DDCIs) with or without entacapone as an adjuvant. This was a retrospective population-based register cohort study in Finland. Male PD patients exposed to levodopa/DDCI with entacapone and patients on levodopa/DDCI without entacapone between 1998 and 2009 were identified from the Finnish Prescription Register. Concomitant treatment with dopamine agonists (DA) and monoamine oxidase B (MAO-B) inhibitors was allowed. PCA cases and PCA deaths were identified from the Finnish Cancer Register and from the Cause of Death Register. PCA Incidence and mortality of PCA were modeled by Cox’s proportional hazards model with adjustments for relevant baseline and time-dependent variables. The robustness of the findings for PCA incidence was evaluated in sensitivity analyses with alternative definitions for exposure and by using a nested case-control study setting with 4-5 individually matched controls randomly selected for each incident prostate cancer case within the cohort. The study cohort consisted of 11 396 male patients. During a mean follow-up time of 4.7 years 359 PCA cases and 89 PCA deaths were observed. Entacapone use with levodopa/DDCI did not increase the risk of PCA incidence [hazard ratio (HR) 1.05,95% CI 0.76-1.44] or PCA mortality (HR 0.93,95% CI 0.43-1.98) when compared to levodopa/DDCI without entacapone. For cumulative entacapone use (exposure >360 days vs. never use) the HR was 0.82 (95% CI 0.56-1.18) for PCA incidence and 1.27 (95% CI 0.60-2.72) for PCA mortality. The results for PCA incidence were found robust in the sensitivity analyses. No increased risk in PCA incidence or PCA mortality was seen in relation to entacapone use.