May 10 (Bloomberg) -- The virus that causes cervical cancer may be linked to throat cancer in people who engage in oral sex, according to a report in the New England Journal of Medicine.

A study in 300 adults found that those infected with the human papillomavirus, or HPV, who had oral sex with more than six partners, were three times as likely to get throat cancer. The research was included in a package of studies and commentary on the virus in today's issue of the journal.

The throat cancer study didn't explore whether Gardasil, the Merck & Co. HPV vaccine approved by U.S. regulators in June, would protect against oral infections. The findings may spur new debate over use of the drug -- already the center of controversy over whether schoolgirls should be inoculated. Oral HPV infection occurs in both men and women who engaged in this type of sex.

``Our results and those of other studies provide a rationale for HPV vaccination in both boys and girls,'' said the researchers, led by Gypsyamber D'Souza, an epidemiologist at the Johns Hopkins Bloomberg School of Public Health in Baltimore.

The number of cancers found on the tonsils and the base of the tongue is on the rise, and ``the widespread oral sexual practices among adolescents may be a contributing factor in this increase,'' the researchers said. If Gardasil also prevents oral infections, there could be a substantial reduction in throat cancers, they said.

Gardasil, which generated $365 million in sales in the first quarter this year, is one of the most-important new products for Whitehouse Station, New Jersey-based Merck as it seeks to offset $800 million in diminished sales from its cholesterol pill Zocor, which lost patent protection in 2006.

Confirmation Needed

One study alone can't prove that HPV triggered the throat cancers, the investigators said. While additional research is needed to confirm the results, the findings are consistent with previous work, the scientists said.

The study compared 100 patients with newly diagnosed cancer of the oropharynx, the back of the mouth including the soft palate, the base of the tongue and the tonsils, with 200 people without the disease, examining any difference in HPV infections.

More than 26 vaginal sexual partners also increased the risk of cancer in people with HPV infections. Smoking and drinking were the main risks for cancer in uninfected patients.

``Our data suggest that oral HPV infection is sexually acquired,'' the researchers said. ``Oral-genital contact was strongly associated with oropharyngeal cancer, but we cannot rule out transmission through direct mouth-to-mouth contact or other means,'' they said.

Cancer Incidence

Every year, about 650,000 people worldwide are diagnosed with head and neck cancers, and 350,000 die from the diseases. In the U.S. each year, almost 7,500 people die from oral cancer and 35,000 are told they have it, according to the American Cancer Society, based in Atlanta.

The New England Journal package also included two studies showing Gardasil, which may face a competition this year from a vaccine from London-based GlaxoSmithKline Plc, provides three years of protection against abnormal cell growth that may turn into cervical cancer.

The studies appear two days after a Glaxo official said the company's experimental HPV vaccine, Cervarix, may be sold before the end of 2007 if it gets a priority review by regulators. The company announced similar study results for its shot at a medical meeting in San Diego.

`Wonderful'

``What is wonderful with these HPV vaccines is that we're seeing a picture of consistency for their effect against the HPV related precancerous and benign lesions that are caused by the targeted HPV vaccine types,'' said the lead researcher, Laura Koutsky, a professor of epidemiology at the University of Washington in Seattle, in a telephone interview yesterday.

Merck has distributed more than 5 million doses of Gardasil since it was approved last June, company officials said. It is covered by federal vaccine programs for uninsured children in all 50 states and the U.S. Centers for Disease Control and Prevention, based in Atlanta, recommends it for girls aged 11 and 12.

New York Mayor Michael Bloomberg, the founder and majority owner of Bloomberg News parent Bloomberg L.P., is an alumnus and benefactor of Johns Hopkins University, whose Bloomberg School of Public Health is named in his honor.

To contact the reporter on this story: Michelle Fay Cortez in Minneapolis at mcortez@bloomberg.net

Last Updated: May 10, 2007 12:09 EDT