7:52 AM
WASHINGTON — A vaccine against the sexually-transmitted disease HPV, which can cause cervical cancer in women, also has been shown to prevent most anal pre-cancers in gay men, according to the results of an international study released Wednesday.
Men who were vaccinated against human papillomavirus developed 75 per cent fewer anal lesions that lead to cancer than their counterparts who were given a placebo, said the study in The New England Journal of Medicine.
The findings were released one day after a U.S. advisory panel urged the Centers for Disease Control and Prevention to recommend routine vaccinations for boys aged 11-12 against HPV.
The disease infects at least half of all sexually active adults and can cause genital warts, but often people with HPV show no symptoms at all.
If caught early, the lesions caused by four particularly virulent strains of the virus can often be removed, preventing cancer from forming. But experts say vaccinating against it before people start to have sex is crucial.
There are nearly 6,000 cases of anal cancer diagnosed annually in the United States, and close to 800 deaths, according to U.S. government health statistics.
"What this trial showed is that those cancers and deaths could be prevented," said lead author Joel Palefsky, a professor at University of California San Francisco and director of UCSF's Anal Neoplasia Clinic.
The study used a sample of 602 gay men between the ages of 16 and 26 from seven countries, including Canada.
Earlier this year, Health Canada approved an HPV vaccine for use in boys and young men in Canada to prevent genital warts and anal cancer, which is currently available by prescription only. The National Advisory Committee on Immunization, which is operated by the Public Health Agency of Canada, is considering recommendations for broader use of the vaccine for Canadian boys and men.
Canadian Cancer Society spokeswoman Gillian Bromfield said Wednesday the organization would consider making changes to its official recommendations on HPV vaccines based on pending Canadian guidelines.
"Canadian Cancer Society experts will be reviewing the HPV Canadian guidelines for males when they are released and we'll update our messaging to Canadians if appropriate," Bromfield said in an email. "For the time being, men should talk to their doctors about whether the vaccine is right from them."
Some provinces, including Quebec, Alberta, Ontario and British Columbia, have a provincial HPV vaccination program for girls in Grade 4 through Grade 9. No provincial programs for males have been implemented.
In the study released Wednesday, which was funded by drugmaker Merck, the participants had at least one, but no more than five sexual encounters. They were randomly assigned either a placebo or a three-shot injection of Gardasil, a Merck-made vaccine.
Gardasil is the only vaccine on the market that is successful in the fight against HPV 6, 11, 16 and 18 in boys and girls. A vaccine made by GlaxoSmithKline, called Cervarix, is approved for use in girls against HPV types 16 and 18.
The trial ran from 2006 to 2008 and included three years of followup, after which those who had never been exposed to HPV showed a 75 per cent lower rate of anal HPV infections and precancerous anal lesions.
Those exposed to one or more of the HPV types that Gardasil aims to prevent saw 54 per cent fewer lesions than those who were not given the vaccine.
"Based on these data, the vaccine works well to prevent HPV infection and precancerous anal disease, and will likely prevent anal cancer in men," said Palefsky.
"The ideal time to begin vaccination would be before initiation of sexual activity, but vaccination may also be useful after initiation of sexual activity."
© Copyright (c) AFP, Photograph by: Thinkstock, canada.com
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