The vaccine Gardasil provides at least short-term protection in men who have sex with men (MSM) against human papillomavirus (HPV) strains known to cause cancer, according to a study presented at the International Papillomavirus Conference in Malmö, Sweden.

Specific strains of HPV, particularly types 16 and 18, have been linked to cervical, penile and anal cancer. HPV types 6 and 11 are believed to be a cause of noncancerous lesions and genital warts.

Gardasil has been shown to significantly reduce infection with these four strains of HPV in young women. As a result, the Centers for Disease Control and Prevention (CDC) recommends that 11- and 12-year-old girls be vaccinated, and that girls and young women between the ages of 13 and 26 also be vaccinated if they’ve not completed a full course of the vaccine. Gardasil, however, hasn’t yet been proved effective in young MSM.

To determine the early response rates of Gardasil in young MSM, Joel Palefsky, MD, from the University of California in San Francisco, and his colleagues, compared the vaccine with a placebo in 602 MSM between the ages of 16 and 26. Regular swabs of the men’s penises and anuses were conducted, as were blood tests. The average follow-up time was one year following the last of the three vaccine injections.

The vaccine was remarkably effective. It reduced the number of external genital lesions by HPV types 6, 11, 16 or 18 by 79 percent. It protected against persistent infection in blood or swab samples by 94 percent. Eighty-nine percent or more of the participants developed antibodies to the four HPV types by month seven.

Palefsky and his colleagues say they are encouraged by these results and look forward to longer follow-up to increase their confidence that the results are lasting.