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By Anne Harding

TUESDAY, June 2, 2009 (Health.com) — Most people have heard about the shot that can protect young girls and women from the human papillomavirus, or HPV, which can lead to cervical cancer. But what about older women?

The picture for older women—meaning mid-20s and up—is a bit murkier. According to a study published this week in The Lancet, an HPV vaccine can indeed protect women ages 24 to 45 from getting the sexually transmitted virus.

But that doesn’t necessarily mean that every woman in this age group needs—or should get—such shots, some experts say. The vaccine is currently approved for use in women and girls ages 9 to 24, and insurers don’t cover it for older women.

In addition, it’s not clear whether the vaccine will actually protect older women from cervical cancer, and it isn’t cheap. The vaccine’s three injections (sold as Gardasil in the United States) cost about $375, and that doesn’t include the office-visit fees that some doctors charge.

It’s definitely possible that Gardasil could benefit older women, says Kenneth Noller, MD, of Tufts Medical Center, in Boston, who wasn’t involved in the research. “This article doesn’t give me enough information to know,” Dr. Noller says. “What we really need to know is if these women who were vaccinated developed less significant disease than women who weren’t vaccinated, and we won’t know this until several years from now.”

Nevertheless, Kevin Ault, MD, an ob-gyn at Emory University School of Medicine, in Atlanta, who helped conduct the new study, says he would recommend Gardasil for older patients who run the risk of being exposed to an HPV infection. He uses the example of someone entering the dating scene after years of monogamy. “Real-life examples come to me all the time,” Dr. Ault says.

Next page: Vaccine doesn't protect women already infected with HPV

Dr. Ault and his colleagues are following 1,911 Colombian women ages 24 to 45 who received the vaccine, and another 1,908 who were given a placebo. None of the study participants had a history of genital warts or cervical disease. (There are more than 100 HPV strains; some cause genital warts, others cause cervical cancer, and others are harmless.) The Lancet study, released this week, is based on about two years of follow-up. The study was funded by Merck, the makers of Gardasil.

Gardasil protects against HPV 6 and 11, which cause most cases of genital warts, and HPV 16 and 18, which cause cervical cancer. However, Gardasil won’t protect women who were infected with HPV before they received the vaccine.

About 3 out of 4 sexually active women become infected with HPV at some point in their lives, but usually the virus goes away on its own without any treatment. The virus, if it persists for a long time, can cause the cell changes that lead to cancer.

Four of the 1,615 women who received the full course of the vaccine developed persistent infection with one of these HPV types, or any disease related to one of the viral strains, compared to 41 of the 1,607 women in the placebo group. The researchers say that the efficacy of the vaccine was “high,” but mostly in terms of protecting against infection—not cervical cancer.

It’s not known if new HPV infections will lead to precancerous cervical changes in older women, says Cosette Wheeler, PhD, a professor of molecular genetics and microbiology at the University of New Mexico School of Medicine, in Albuquerque. “We understand that people get infections, we understand that people develop low-grade abnormalities, but we also understand that the amount of precancer is very low in these populations,” says Wheeler, who has conducted extensive research on HPV infection and cervical cancer.

Also, Wheeler says, the current study is simply too small to show whether the vaccine did indeed reduce precancerous changes in the older women, because this occurs so rarely. “If you have such a low reality of an outcome, it’s probably not a useful or cost-effective application to extend the age of vaccination,” she explains.

Dr. Ault argues that the vaccine makes sense for older women who have new sex partners later in life. “The best argument against getting this vaccine more widely is that it’s expensive," he says. "The guys aren’t out there getting Pap smears, so who knows what’s going on with them?”

Regardless of whether they have the HPV vaccination, women should still get routine Pap smears. That test looks for cancerous and precancerous changes in the cervix so that they can be caught and treated at an early stage.


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