Aspirin use and the risk of prostate cancer: a meta-analysis of 24 epidemiologic studies

Several epidemiologic studies were performed to clarify the protective effect of regular aspirin use on prostate cancer risk; however, the results remain controversial. Therefore, we conducted this meta-analysis to assess the association between regular aspirin use and risk of prostate cancer. Electronic databases including PubMed, EMBASE and Cochrane Library were searched between January 1966 and April 2013 to identify eligible studies. Pooled relative ratios (RRs) and 95 % confidence intervals (CIs) were computed to assess the influence of aspirin use on prostate cancer risk. All statistical tests were two-sided. A total of 24 observational studies including 14 case-control studies and 10 cohort studies were eligible for this meta-analysis. Regular aspirin use was associated with reduction in overall and advanced prostate cancer risk (pooled RR 0.86, 95 % CI 0.81-0.92; pooled RR 0.83, 95 % CI 0.75-0.91, respectively). When we restricted our analyses to studies with long-time regular aspirin use (equal or more than 4 years), reverse association became stronger (pooled RR 0.82, 95 % CI 0.72-0.93; pooled RR 0.70, 95 % CI 0.55-0.90, respectively). Our findings suggest that regular, especially long-time regular aspirin use may reduce the risk of overall and advanced prostate cancer. Considering the limitation of included studies, further well-designed large-scaled cohort studies and RCTs are required to draw more definitive conclusions.