Purpose: 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.
Methods: 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.
Results: 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).
Conclusions: 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.