When parents put their baby boys under the knife for circumcision, it's usually for religious or cultural reasons, but mounting evidence suggests that the removal of the foreskin might also serve a public health purpose: reducing the spread of human papillomavirus (HPV).
Not only does past research show that circumcised men are 32 to 35 percent less likely to contract HPV, but a new study published in the Lancet Thursday shows that women whose partners are circumcised are 28 percent less likely to become infected with HPV.
This finding has particular weight considering that persistent infections with high-risk strains of HPV in women can lead to cervical cancer. Cervical cancer is the leading cause of cancer deaths internationally for women.
Over the past five years, randomized controlled trials have shown that circumcision decreases the risk of HIV, HPV, and herpes. In women it reduces the risk of bacterial vaginosis, trichomoniasis, and now HPV. Though these studies have been done in African countries, their findings, including Thursday's, support observational studies already performed in the U.S., says study author Dr. Aaron Tobian of Johns Hopkins University.
"Many will argue that these findings are in Africa and they do not represent the U.S., however almost all of the supporting observational studies for this area were performed on U.S. populations," he says. "We believe the cumulative scientific evidence supporting circumcision is now overwhelming."
Given this evidence, Tobian says it's disquieting to see the rate of circumcision in the U.S. decline as it has in recent decades. Though estimates vary between data sources, one CDC presentation put in-hospital neonatal circumcisions (which leaves those done in the Jewish ritual circumcisions) at 32.5 percent in 2009, compared to 56 percent in 2006 and somewhere around 65 percent in the 1980s.
The debate over whether or not to circumcise newborn boys has been a passionate one in the U.S., with some anti-circumcision "inactivists," such as San Franciscan Lloyd Schofield, proposing to ban the practice. Though proponents often cite cleanliness and lowered risk of infection as reasons to favor circumcision, the practice has not yet become one of public health import in the U.S. as it has for certain developing nations.
The question, in light of growing concerns over HPV and increasing evidence of its moderately infection-protective effect, is whether it should be.
In the study, HIV-negative Ugandan men and women who were in monogamous relationships were randomized into a treatment group, where the men were circumcised, or a control group, where men were left uncircumcised. After two years, 28 percent of the women whose partners had been circumcised had high risk HPV infection compared to 39 percent of those whose partners had remained uncut. This constitutes a 28 percent increased risk of infection for those women who were sexually active with uncircumcised partners.
So what is going on here? There are several possible explanations for why the foreskin may be promoting infection and transmission of infection to female partners, Tobian says. There may be micro-tears in the skin that lead to higher viral infection. Perhaps the quality of foreskin allows for easier infection of epithelial cells. It's also possible that the moist environment beneath the foreskin may be favorable to infection.