Circumcision may help prevent prostate cancer in some men, according to new research. 

The findings, which are published in BJU International,add to a growing list of advantages to circumcision. Besides advanced age, African ancestry, and family history of prostate cancer, no other risk factors for prostate cancer have been definitively established. This has fuelled the search for modifiable risk factors.

Marie-Élise Parent, PhD and Andrea Spence, PhD, of the University of Quebec’s INRS-Institut Armand-Frappier, led a team that designed an observational study to investigate the possible association between circumcision and prostate cancer risk. 

Their study, called PROtEuS (Prostate Cancer and Environment Study), included 1,590 prostate cancer patients diagnosed in a Montréal hospital between 2005 and 2009, as well as 1618 healthy control individuals. In-person interviews were conducted to gather information on sociodemographic, lifestyle, and environmental factors.

Circumcised men had a slightly lower risk, albeit not statistically significant, of developing prostate cancer than uncircumcised men. Circumcision was found to be protective in men circumcised when they were older than 35 years, with the procedure decreasing their risk by 45%. 

A weaker protective effect was seen among men circumcised within 1 year of birth, with the procedure decreasing their risk by 14%. The strongest protective effect of circumcision was recorded in Black men, who had a 60% reduced risk if they were circumcised, but no association was found with other ancestral groups. 

“This is a particularly interesting finding, as Black men have the highest rates of prostate cancer in the world and this has never been explained,” said Dr Parent. “This novel finding warrants further examination in future studies that have a larger number of Black participants.” 

Dr Parent noted that circumcision may reduce the risk of contracting and maintaining a sexually transmitted infection, which has been postulated to be a risk factor for prostate cancer. This may explain the reduced risk of prostate cancer observed in males circumcised at a younger age prior to any potential exposure to infection. 

“We do not know why a protective effect was observed for men circumcised after the age of 35. These men may have had a pathologic condition of the foreskin that lead to them being circumcised,” she said.