Researchers at the University of Montreal and the INRS-Institut-Armand-Frappier have shown that men circumcised after the age of 35 were 45% less at risk of later developing prostate cancer than uncircumcised men.
This is one of the findings that resulted from a study undertaken by Andrea Spence and her research directors Marie-Élise Parent and Marie-Claude Rousseau. The researchers interviewed 2114 men living on the Island of Montreal. Half of them had been diagnosed with prostate cancer between 2005 and 2009, while the others participated in the study as the control group. The questions covered their lifestyle and medical history, if they were circumcised, and if so, the age at which the operation had been performed.
Greater benefit for Black men
Across the board, the participants who were circumcised were 11% less likely to later develop a prostate cancer compared to those who weren't. The size of the reduction is not statistically significant. "This proportion reflects what has been shown in other studies," Parent explained. However, babies who were circumcised before the age of one were 14% less likely to develop prostate cancer. Moreover, the removal of the foreskin at a young age provides protection, over the long term, against the most aggressive forms of cancer.
Prostate cancer is rare amongst Jewish or Muslim men, the majority of whom are circumcised. While the specific causes of this cancer remain unknown, three risk factors have been identified: aging, a family history of this cancer, and Black African ethnic origins.
Amongst the 178 Blacks who took part in the study – of whom 78% were of Haitian origin – the risk of prostate cancer was 1.4 times higher than amongst Whites. 30% of the Black men were circumcised compared to 40% of the White men. Interestingly, the protective effect of the circumcision was limited to the Black men, whose risk of developing prostate cancer was decreased by 60%, with a very significant statistical effect.
Circumscribing the discovery
Researchers do not know what mechanism enables circumcision to protect men from prostate cancer. However, many studies have shown that this operation reduces the risk of acquiring a sexually transmitted infection (STI). "Unlike the skin that covers our bodies, the inner surface of the foreskin is composed of mostly non-keratinized mucosal epithelium, which is more easily penetrated by microbes that cause infections," Parent explained. Removing the foreskin could therefore reduce the risk of an infection that might be associated with prostate cancer. In any case, the protective effect of circumcision (in particular the effect observed in the Black population) must be confirmed by other studies, especially in consideration of the relatively few Black men who participated in research.
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