Prostate cancer risk and nonsteroidal antiinflammatory drug use in the Finnish prostate cancer screening trial

Background: The association between nonsteroidal antiinflammatory drugs (NSAIDs) and prostate cancer risk remains controversial. We examined the risk among NSAID users in 78 615 men in the Finnish Prostate Cancer Screening Trial. Methods: We obtained information on NSAID prescription usage from Finnish nationwide prescription database and on over-the-counter use by a questionnaire. Prostate cancer cases were identified from the Finnish Cancer Registry. Results: Prostate cancer risk was elevated among current NSAID prescription users irrespective of screening (hazard ratio (HR) = 1.45, confidence interval (95% CI) = 1.33-1.59 and HR = 1.71, 95% CI = 1.58-1.86 in the screening and control arm, respectively), but not for previous use of NSAIDs. The risk increase was similar among coxib and acetaminophen current users, and stronger for metastatic prostate cancer (HR = 2.41, 95% CI = 1.59-3.67 and HR = 3.44, 95% CI = 2.60-4.55 in the screening and control arm, respectively). Previous use of NSAIDs, aspirin use and over-the-counter NSAID usage were not associated with prostate cancer. Conclusions: Differing association for current and previous use suggests that the risk increase is unlikely to be directly caused by the medication, but may be due to the conditions indicating NSAID prescription usage, such as symptoms of undiagnosed prostate cancer. To reduce inconsistency between the study outcomes, future epidemiological studies on NSAID use and prostate cancer risk should assess the indications for NSAID usage.