The human papillomavirus (HPV) can be much more than a pain in the butt: The common virus currently causes 5% of the world's cancers. But a vaccine exists, and it's estimated that if males were vaccinated, the rate of anal cancer would fall by 60%. As reported by the website aidsmap, a study of gay men in Ireland has found that half to two-thirds of gay men, whether HIV positive or negative, would benefit from getting HPV vaccines to protect themselves from the two most common cancer-causing strains of the virus.
A much higher proportion of gay men than the general public is already living with HPV infection, specifically the strains most associated with cancer. While HIV-negative gay men are 17 to 35 times more likely to have HPV than the general public, HIV-positive gay men are 35 to 70 times more likely to contract HPV -- and are at much higher risk of HPV progressing to anal cancer. The best way to prevent HPV infection is with the vaccine Gardasil. Gardasil, a "quadrivalent" vaccine, protects against the four most common HPV strains: types 6, 11, 16 and 18.
The study included 194 Irish gay men at a hospital in Dublin, 99 of whom were HIV positive and 95 HIV negative. Aside from serostatus the two groups of men were similar, except the HIV-positive men tended to be older. The HIV-negative men were an average of 32 years old, had about seven sexual partners in the past year, and about 40% reported consistent condom use in the past year. The study's HIV-positive gay men averaged about 40 years old, had about eight sexual partners in the past year, and 43% reported using condoms for every sexual encounter.
In the end, the study found that 69% of men had at least one type of HPV infection, with more HIV-positive men having at least one strain of HPV than HIV-negative men. Though a large percentage had at least one type of HPV, a minority of men had infection with HPV16 and HPV18, the two most commonly-found, virulent cancer-causing strains. Just under half of HIV-positive men had either one or both of these strains, compared to around a third of HIV-negative gay men. The researchers stressed that those already infected with one of the cancer-causing HPV types could benefit marginally from the vaccine.
Twelve percent of HIV-positive men had both HPV16 and HPV18, while none of the HIV-negative men did. The human body naturally develops an immune response to the virus that usually causes it to flush out of a person's body over a period ranging from a few months to years. The HIV-positive men in this study may have had more cancer-causing strains because their bodies may take longer to flush out HPV naturally.
Researchers also noted that the difference in the amount of HPV may be due to the difference in age between the HIV-negative and HIV-positive cohorts. The likelihood of having a cancer-causing strain of HPV rose with age, with a quarter of 17- to 24-year-olds having HPV 16, 18 or 31, while half of men over 35 had one or more of the three. The same was not true for all HPV strains, however. More young gay men had wart-causing HPV than older gay men.
Was it very common to have both cancer-causing and wart-causing strains? Unsurprisingly, men who had a previous STI diagnosis or anal warts were more likely to have both. Thirty-six percent of men who always used condoms had at least one cancer-causing HPV strain, while 44% who sometimes used condoms and 56% of those who never used condoms (a small minority) had both strains.
There was no correlation between having HPV and type of sex. Men who only had oral sex were just as likely to have HPV as men who only had anal sex.
Part of the title of the study was "A Call to Action," and the researchers do indeed want their research to have implications. The researchers showed that at least half of HIV-positive gay men and two-thirds of HIV-negative gay men could benefit from the vaccine to prevent cancer.
The study was presented to the U.K.'s Joint Committee on Vaccination and Immunisation, which is considering a recommendation for adolescent boys and gay men to receive the HPV vaccine. The HPV vaccine has been licensed for young men under the age of 26 in the United States since 2010.
The researchers added, "Emerging patterns of HPV-related diseases strengthen the call for universal vaccination of boys and girls with consideration of catch-up and targeted vaccination of high-risk groups such as MSM (men who have sex with men) and those with HIV infection."
Mathew Rodriguez is the community editor for TheBody.com and TheBodyPRO.com.
Follow Mathew on Twitter: @mathewrodriguez.