Men Who Have Sex With Men at High Risk of Certain Anal HPV Infections

Men who have sex with men (MSM) are at an increased risk for nontransient infection with human papillomavirus (HPV) that carries a high risk of cancer, and that risk increases as their number of lifetime partners increases, according to a recent study published in Clinical Infectious Diseases.

Alan G Nyitray, PhD, Assistant Professor of Epidemiology and Human Genetics & Environmental Sciences at the Center for Infectious Diseases at the University of Texas School of Public Health in Houston and colleagues performed a prospective, observational sub-study of 406 HIV-negative MSM recruited from the larger HPV Infection in Men (HIM) Study that ran between June 2005 and February 2009.

The researchers collected and genotyped 406 anal samples from HIV-negative MSM between the ages of 18-64 years from Mexico, the United States and Brazil. Over a 2-year span, researchers evaluated samples from MSM every 6 months for 2 or more clinic visits.

These men were placed in two groups –  70 men who only have sex with men (MSOM) and 336 men who have sex with women and men (MSWM). Researchers reported defining persistence as 12 months or more type-specific duration and either began as a prevalent or incident infection.

Dr Nyitray and colleagues reported an 82% retention rate in the study with a median follow-up of 2.1 years. Nineteen percent of MSOM had the 9-valent vaccine for HPV, while only 8% of MSWM had been vaccinated.

The research team noted no difference in duration of HPV-16 infection, which was reported as 6.9 months, between MSOM and MSWM after combining the men from the 2 groups. Of 106 men with prevalent high-risk infection, researchers said that 36.8% had the infection for at least 24 months. In men with prevalent HPV-16, 29.6% had the infection for a minimum of 24 months.

“Persistence of high-risk HPV was associated with number of male anal sex partners and inversely associated with number of female sex partners,” researchers reported in the study. In an analysis controlled for mitigating factors, men who reported 20 or more lifetime partners had more than twice the change of having high risk HPV. The same amount of risk was found in MSM who had one or more anal sex partners in the last 3 months.

In a brief interview with Infectious Disease Advisor, lead author of the study Dr Nyitray said that “incident infections are likely to clear more quickly,“ but he added, “an increased number of sex partners may increase chances of persistent HPV.”

Researchers noted in the study that while men who only have sex with women may be protected via herd immunity from vaccinated women, MSM are at particular risk for HPV, especially since men are not as routinely vaccinated for HPV as women and the vaccine in only approved for adults under the age of 26 in the United States. Vaccine rates among MSM should be targeted as a public health issue and vaccination rates need to increase.

Dr Nyitray explained that the study was important because the results could affect future anal cancer screenings that would use HPV DNA testing so that those with high risk HPV can be selected to be screened for cancer. In addition, they also noted that number of sex partners is a behavior that can be modified to reduce the risk of infection.

Reference

1. Nyitray AG, Carvahlo da Silva RJ, Chang M et al. Incidence, duration, persistence, and factors associated with high-risk anal human papillomavirus persistence among HIV-negative men who have sex with men: a multinational study. Clin Infect Dis. 016;62(11):1367–74.