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.
Circumcise Men, Benefit Women
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.
"Once you remove that area," Tobian says, "it's harder for the virus to enter and infect."
And when the infection rate is lower for men, they are less likely to transmit this infection to their female partners. This is especially important, Tobian says, because an HPV infection -- unlike HIV can clear and become non-active.
"Viruses are permanent, but the activity of the virus is what we're more concerned with," says director of Gynecology at Albert Einstein Medical School Dr. Erika Banks. "It's not really HPV that's the problem, it's the persistence of infections with high-risk strains."
Study authors cautioned, however, that while circumcision reduced the risk of infection, it did not eliminate the need for other forms of protection from sexually transmitted diseases. They said men should still use condoms and women should get the HPV vaccine.
Circumcision as a Public Health Debate
For developing nations with particularly high levels of HIV and HPV, circumcision may offer a cost-effective means of reducing transmission rates in an environment where access to vaccines and medical care are lacking.
"Circumcision may offer a low cost minimal risk one-time procedure that could decrease the transmission of the virus that can cause cervical cancer" in developing nations who do not have access to regular screenings, says Banks.
In Africa circumcision programs to provide the procedure to adult males have been "ramping up," says Dr. Thomas Quinn, co-author on the study and researcher for Johns Hopkins University and the National Institute of Allergy and Infectious Diseases. For instance in Kenya, more than 250,000 males have been circumcised so far as part of HIV prevention programs sponsored by the government.
Back in the U.S., the health benefit may not be as "imminently relevant," she says, but the evidence is compelling enough nonetheless to consider strengthening recommendations for circumcision.
American Academy of Pediatrics recommendations say the data are "not sufficient to recommend routine neonatal circumcision," and as a result, Medicaid in many states does not cover the practice. The academy is currently reviewing the recent data emerging from African studies like Thursday's in order to update the guidelines.
"The data on sexually transmitted diseases [and circumcision] are the data we didn't have five to ten years ago when we were making the recommendations," says Dr. Doug Diekema, a member of the academy's circumcision task force. He says new recommendations will likely come out within a year. Though he couldn't say for certain whether the academy's stance on circumcision would change, he said he "wouldn't be very surprised if the academy leaves it ultimately up to the parents and says it's the physician's job to make sure the parents understand fully the benefits and risks of this procedure."
Study authors are hoping for a more substantial change in policy, however.
"We are not at all mandating that everyone should be circumcised, but we disagree that the evidence is 'conflicting' as the AAP says. We believe the public should be aware of the existing evidence and it should be a decision among parents that are informed of this evidence," Tobian says.
"There's no doubt that male circumcision provides a certain degree of protection against sexually transmitted diseases," adds Quinn, "and male circumcision needs to be reevaluated by leading health authorities as to its true public health benefit, not just to men but to future female partners."