A vaccine that is FDA approved to protect young women from HPV (human papillomavirus), which is the leading cause of cervical cancer, can HPV infection in boys as well.
Thursday, Feb. 3, 2011
In an industry-sponsored multinational randomized clinical study conducted among more than 4,000 boys and young men, the vaccine also prevented infection by the four HPV strains, according to Dr. Anna Giuliano, of the H. Lee Moffitt Cancer Center and Research Institute in Tampa, Fla., and colleagues.
Giuliano and colleagues reported the results in the Feb. 3 issue of the New England Journal of Medicine
The vaccine has been approved to prevent cervical, vulvar, and vaginal cancer, as well as precancerous lesions caused by HPV types 6, 11, 16, and 18, in girls and women ages 9 through 26.
It's also approved to prevent genital warts caused by types 6 and 11 in both males and females.
In December, 2010, on the recommendation of an advisory panel, the FDA expanded the indication to include anal cancer and anal intraepithelial neoplasia (AIN) grades 1, 2, and 3 caused by the four HPV vaccine types.
Outside experts greeted the current report with a mixture of enthusiasm and caution.
In an accompanying Perspective article, Dr. Jane Kim, of Harvard School of Public Health, said the report is "cause to celebrate the extraordinary potential" of HPV vaccination to improve public health.
But Kim and others added that the expense of the vaccine — about $400 for the complete series of three shots — combined with concerns about the durability of its immune response gives it an uncertain future as a preventive measure in boys and men.
Giuliano and colleagues studied 4,065 healthy boys and men, ages 16 to 26, from 18 countries in a randomized, placebo-controlled, double-blind trial of the vaccine. The primary efficacy goal was to show that the vaccine reduced the incidence of external genital lesions related to HPV types 6, 11, 16, or 18.
The volunteers were analyzed on an intent-to-treat basis, all participants who got either vaccine or placebo, as well as per-protocol -- which included only those who got vaccine or placebo and were negative for 14 strains of HPV, including the four vaccine strains, at baseline. The analyses were meant to mimic the general population and boys before their first sexual encounter, respectively.
But a major shortcoming of the study was the limited follow-up, according to Dr. Diane Harper, of the University of Missouri Kansas City.
In an e-mail to ABC News/MedPage Today
While the researchers reported that levels of anti-HPV antibodies peaked seven months after the last shot, Harper noted they gave no information on how quickly those levels tailed off. In trials among girls and women, she said, some women lost immunity to vaccine strains within five years.
The bottom line, she said, is that the vaccine is effective in males against genital warts, a non-life-threatening condition that is one-tenth as common as abnormal Pap smears among women -- but has yet to be shown to be effective against more serious disease.
On the other hand, the study was well done, rigorous, and adds important information to the discussion of whether to strengthen the current permissive recommendation to vaccinate boys, commented Dr. William Schaffner, of Vanderbilt University School of Medicine in Nashville, Tenn.
However, the data by themselves are not enough to "move the needle" toward a recommendation for universal vaccination, Schaffner said in an e-mail to ABC News/MedPage Today
Like most experts reached by ABC News/MedPage Today
The study was supported by Merck, the National Center for Research Resources, and the NIH. Giuliano reported financial links with Merck, as did several other authors. Several authors also are employees of the company.
Kim did not report any conflicts.
This article was developed in collaboration with ABC News.
Learn more in the Everyday Health Sexual Health Center.