17 May 2011
A CUT ABOVE THE REST: RESEARCHERS SHOW THAT CIRCUMCISION PREVENTS CANCER OF THE CERVIX
Women in the developing world looking for protection from cervical cancer have another reinforcement to add to their arsenal: male circumcision. The Johns Hopkins Bloomberg School of Public Health researchers have finished a multiyear study that shows the efficacy of male circumcision as a means of reducing the rate of HPV infection among women. Human papillomavirus (HPV) can cause genital warts and cervical cancer. In the developing world, where 85 percent of infections occur, the situation is dire: WHO estimates that about 33 percent of East African women are harboring HPV. Cervical cancer is the leading cause of cancer death among women in Uganda, where the study took place.
Women partnered to circumcised men have a 25 to 30 percent reduction over time in the number of HPV infections. Though encouraged by the finding, the researchers caution that couples should still practice other forms of safe sex. “Don’t think of this as a magic bullet,” she says. “It’s part of a program of protection.” In the study, 5,000 uncircumcised HIV-negative men enrolled, together with their HIV-negative female partners.
Everyone was tested for infections at the beginning, middle, and end of the study. Circumcised males had lower rates of HPV infection, likely because the procedure makes carrying the disease more difficult, says Wawer. And, as suspected, so did their female partners. The parallel effect occurred because male circumcision both reduced the number of new male infections and increased the proportion of men with HPV at the time of enrollment that subsequently cleared the virus.
“We hypothesize that the foreskin mucosa is an important site for infection,” notes Wawer. “Without this focal site, there is higher clearance at other sites along the male genital tract and less reinfection of other sites by the virus when it is no longer shed by [cells within] the foreskin mucosa.” Since fewer men were infected, fewer transmitted HPV to their partners. A bonus: Wawer says that about 40 percent of women in the study reported being more sexually satisfied after the man’s circumcision, mainly because of better hygiene.
She and her colleagues have been studying a broad range of HIV-related matters since the late 1980s in the Rakai region of Uganda, where they founded the Rakai Health Sciences Program. The researchers made headlines several years ago with a study showing that circumcision dramatically reduced men’s chances of contracting HIV from infected female partners.