FDA Approves Cervical Cancer Vaccine

Merck & Co.'s Gardasil Can Be Used On Women Ages 9-26

(WebMD) 
GlaxoSmithKline says it plans to seek FDA approval for Cervarix by the end of the year. Early studies find that this vaccine, too, is extremely safe and effective.

Both Merck and GlaxoSmithKline are WebMD sponsors.

Pap Screening Still Needed

Despite its potency, Gardasil won't prevent every cervical cancer or every HPV infection. There are some 100 HPV strains out there. Those covered by the vaccine are the worst offenders, but not the only ones.

Neither Gardasil nor Cervarix prevent disease in people already infected with the virus. Perhaps as many as 80 percent of adults have been exposed to at least one strain of HPV, Kahn says. For reasons not fully understood, only a minority of people with HPV get cervical cancer or warts.

"These vaccines only prevent infection. They do not prevent disease once you are already infected with the virus," Kahn says. "The vaccines do not treat precancerous conditions."

This means that while the vaccines undoubtedly will prevent many of the annual 3,700 U.S. and 233,000 worldwide cervical-cancer deaths, it will not end cervical cancer, genital warts, or the spread of other HPVs.

"One of the points I am going to try to get across to teens is to stress that even after getting the vaccine, they must continue to get regular Pap screening," Kahn says. "Some vaccinated women will still have abnormal Pap tests. It does not mean the vaccine is not working. A lot of abnormal Paps are caused by HPVs that are not in the vaccines."

The Role of Parents

Vaccines don't work if people don't use them. Researchers think the vaccines will work best if given to teens before they become sexually active -- that is, at ages 11 to 13.

HPV is a sexually transmitted disease. Will parents object to vaccinating their teens?

Some will -- but the vast majority won't, predicts Gregory D. Zimet, Ph.D., professor of pediatrics and clinical psychology at Indiana University School of Medicine, Indianapolis. Zimet has studied parental attitudes toward vaccines, including vaccines that would protect against sexually transmitted diseases.

"There has been this idea that giving an HPV vaccine to teens might be seen by parents as giving their daughters permission to have sex -- or that it might lower some kind of barrier and lead to a sense of safety that would lead that young adolescent to engage in sex that they would not otherwise have," Zimet tells WebMD.

But when Zimet and colleagues asked parents what their concerns would be about an STD vaccine, this wasn't a common opinion. Instead, parents wanted to know how safe the vaccine was, how well it worked, and whether the disease it prevented was serious.

"There had been some concern that doctors might be reluctant to prescribe STD vaccines because of anticipated parental opposition," Zimet says. "But research indicates parents have great eagerness to have their children vaccinated against these diseases."

SOURCES Longworth, M.S. Microbiology and Molecular Biology Reviews, June 2004; vol 68: pp 362–372. Jessica Kahn, MD, MPH, associate professor of pediatrics, Cincinnati Children's Hospital Medical Center, Ohio. Gregory D. Zimet, PhD, professor of pediatrics and clinical psychology, Indiana University School of Medicine, Indianapolis. News release, American Cancer Society.