Meta-analysis: Male-male anal sex and having HIV are major predictors of anal human papillomavirus infection

Anal human papillomavirus (HPV) infection, especially HPV16, is the main cause of anal cancer. Anal sex increases the infection, and it is worsened by HIV-related immunosuppression.

Approximately 35,000 HPV-related anal cancers are diagnosed annually worldwide, including 17,000 among males. Anal cancer rates are increasing in several high-income countries, which might be due to changes in sexual behavior.

In the U.S., most of the increase among young males is due to human immunodeficiency virus
(HIV) infection.

Researchers recently conducted a meta-analysis of 79 studies with a total of almost 24,000 patients.

Among people who did not have HIV, rates of HPV16 was higher among men who have sex with men (MSM) (14%) than among men who have sex with woman (MSW) (3%).  The same was true for HIV-positive men -- 30% for MSMs versus 11% for MSWs.

So same-sex preferences and being HIV-positive are both strong predictors having HPV16 infection. The authors conclude that to prevent anal cancer, focus should be placed on gay men with HIV.