Two new studies suggest that male circumcision may assist in the prevention of human papillomavirus (HPV) infection, particularly infection with the high-risk subtypes associated with cervical, penile, and other cancers. Both studies are published in The Journal of Infectious Diseases.
High-risk subtypes of HPV have been estimated to be present in 99.7% of cervical cancers worldwide. Evidence has shown that women with circumcised partners have a reduced risk for genital cancer. Two new studies sought to discover if HPV infection is more likely to occur in uncircumcised compared with circumcised men.
Bertran Auvert and his team of researchers in France and colleagues from South Africa studied data from a trial conducted in Orange Farm, South Africa. Uncircumcised men aged 18 to 24 years were randomised into either an intervention group, to be circumcised, or a control group, to remain uncircumcised. During this study, urethral swab samples were collected and analysed for presence of HPV among men followed up for 21 months. Information about sexual behaviour was also collected.
Less genotypes in circumcised men
Auvert and colleagues found that the percentage of high-risk HPV genotypes was lower in the circumcised group than in the control group. The most important implication, according to researchers, was that “reducing the frequency of HPV infection among men will reduce the risk of exposure in their female sexual partners.”
A second study by Carrie Nielson at the Oregon Health & Science University and colleagues at the University of Arizona, H. Lee Moffitt Cancer Centre and Research Institute, and the Centres for Disease Control and Prevention tested more than four hundred men aged 18 to 40 years in two US cities from 2002 to 2005. Sixteen percent of participants were uncircumcised. Researchers tested for HPV in skin swabs of the anogenital area and semen samples in participants with no HPV symptoms (such as warts or lesions).
Risk reduced by half
Investigators found that circumcised men were about half as likely to have HPV as uncircumcised men, after adjustment for other differences in the two groups. These results demonstrated that lack of circumcision is associated with cervical cancer because of the increased risk of HPV infection. Nielson suggested that it may be useful to consider circumcising newborn boys in order to decrease the risk of HPV infection for them and their future partners. “Parents are not currently advised of this risk,” she said. “These studies contribute to the evidence that might help to inform that decision.”
In an accompanying editorial, Ronald H. Gray of Johns Hopkins University said that the evidence was persuasive but not entirely consistent, and that it may be premature to promote circumcision as a way to prevent HPV infection in men and to protect female sex partners from infection. He advised that policy decisions should await results from two ongoing trials of male circumcision. Alternatively, Gray noted that consistent evidence has suggested that male circumcision reduces the frequency of HIV infection in men.
According to Nielson, the findings they reported present compelling arguments to promote male circumcision in developing countries where circumcision is not widely used and the HIV epidemic is severe. Additionally, she said, it is “the first clear demonstration of the indirect but substantial beneficial effect of male circumcision for women.” The authors of both studies and the editorialist agreed that more studies will be needed to confirm the efficacy of male circumcision in HPV prevention.– (EurekAlert!)