Summary: Circumcision and prostate cancer: a population-based case-control study in Montreal, CanadaDrs. Andrea Spence, Marie-Claude Rousseau, Pierre I. Karakiewicz, Marie-Elise Parent
While there are essentially no known modifiable risk factors that could lead to the prevention of prostate cancer, it is known that prostate cancer is very rare in Jewish men – who are all circumcised for religious reasons at birth. This has led to the hypothesis that circumcision might protect against prostate cancer. Moreover, STIs have been associated with an increased prostate cancer risk, and circumcised men have a lower chance of acquiring an STI compared to men with foreskin. Drs. Andrea Spence, Marie-Claude Rousseau, Pierre I. Karakiewicz, and Marie-Elise Parent set out to investigate this association using the PROtEuS study as their sample population. Their goal was to see whether this link existed in the context of a large population-based case-control study, whether age at circumcision influences the prostate cancer risk, and whether race modifies the circumcision-prostate cancer relationship.
The findings were interesting on several levels: circumcised men had a slightly lower, though not significant, risk of developing prostate cancer. More telling was that circumcision was found, for the first time, to be highly protective in those circumcised after age 35, while much less protective for those circumcised within one year of birth. The researchers did notice some indication, however, that circumcision before age 1 may be protective against more aggressive prostate cancer. All associations, it should be noted, were seen to be unrelated to STI history. Lastly, the strongest protective effect of circumcision was found in Black men.
This last observation is especially important since it is well-documented that prostate cancer has a greater incidence among men of African ancestry, but nobody knows why. As expected, the Black men in this study had excess risk of prostate cancer compared to White men. Here’s the kicker: Black subjects in this study were also less likely to have been circumcised than White men – and only one study has so far examined whether race modifies the circumcision-prostate cancer association. This may be one factor responsible for the difference in prostate cancer risk according to ancestry. These novel findings evidently warrant further research into the variation in the effect of circumcision on prostate cancer risk by ancestry and age at circumcision, with attention to reason for circumcision.
Future investigations could build on this study by verifying circumcision status through medical records, as opposed to the self-reporting used here, and by collecting the reasons why adults were circumcised (which could help assess whether the observed protective effect was limited to men with medical indication for surgical removal of the foreskin).Yet, these results are highly commendable given this was one of the largest ever studies examining this issue, the experience of the interviewers, the relatively high response rates, and the comprehensiveness of the data collected that allowed for the accounting of factors that might skew the findings – something that none of the other six studies that researched this topic had done before.