A recent investigation suggests that circumcision may help keep men away from prostate cancer. ”Previous reports on the relationship between male circumcision and prostate cancer have not been uniform,” Dr. NoelPabalan said in an email to Reuters, “and major studies have yielded varying results, which we tried to address through meta-analysis to statistically determine the association between the two and use it to obtain more precise estimates.” The study, published online July 28 in the journal Prostate Cancerand Prostatic Disease, encompassed seven case-control studies totaling 8,633 individuals to examine the association between prostate cancer and circumcision, from the United States, United Kingdom, and Canada. All but two of the studies reported a decreased risk of prostate cancer in circumcised men. Only three of these studies, however, found statistically significant differences. Overall, there was a slight (12%) non-statistically significant reduction in the risk of prostate cancer in circumcised men. However, the lack of statistical significance and heterogeneity was eliminated after outlier analysis of the overall effect and removal of three studies (OR, 0.90; p=0.04). ”The 17% risk reduction was still statistically significant for the subgroup of the population after PSA testing, a group that included men over 40 years of age and blacks.” Dr. Pabalan said. ”The stability of the risk reduction observed in key subgroups suggests that the effect of circumcision on reducing prostate cancer is most likely to be observed in the following subgroups: those following PSA testing; population-based studies; and studies conducted in blacks.” The researchers noted that all of the studies used in the analysis were retrospective, a limitation of this study. “We found no reports of prospective cohort studies, and an even greater limitation is that circumcision in all of these studies was self-reported, not by medical examination, and therefore subject to misclassification.” Despite these limitations, this is the first meta-analysis of the association between circumcision and prostate cancer. If the low risk of prostate cancer in circumcised individuals is facilitated by a reduction in sexually transmitted diseases or prostate inflammation/infection, “then the timing of circumcision is important and needs to be performed before sexual intercourse occurs.