Gardasil highly effective at preventing pre-cancerous anal lesions in gay men

The human papillomavirus (HPV) vaccine Gardasil is highly effective at preventing pre-cancerous anal lesions in younger gay men, according to the results of a study presented to a recent conference.

Delegates to the European Research Organization on Genital Infection and Neoplasia Congress were told that Gardasil reduced the risk of pre-cancerous anal lesions by 78% in a Phase III, randomised, placebo-controlled trial involving gay men, and other men who have sex with men, aged between 18 and 26.

Gay men, especially those with HIV, have higher rates of anal cancer than those seen in the general population, therefore the high efficacy of the vaccine is encouraging.

Research involving younger women has shown that Gardasil is highly effective at preventing pre-cancerous and cancerous cervical cell changes caused by HPV. Gardasil provides protection against four high-risk types of the virus: HPV 6, 11, 16 and 18.

Investigators wished to determine the efficacy and safety of the vaccine in younger gay men.

The randomised, placebo-controlled trial involved 598 men. None were infected with HPV strains 6, 11, 16 and 18 on entry to the study. Half were provided with two doses of the vaccine, the others with a placebo. They were then followed for an average of two and a half years and rates of pre-cancerous anal cell changes and anal cancer were compared between the two groups.

High-risk HPV-associated pre-cancerous cell changes were detected in five men who received Gardasil compared to 24 of the individuals who were given the placebo. The investigators therefore calculated that Gardasil reduced the risk of such cell changes by 78%.

No patient in either study arm developed anal cancer.

Gardasil appeared safe, with similar numbers of patients in the vaccine and placebo study arms reporting severe side-effects.