But the rate of some of these cancers didn't go down as quickly as others, and, in the case of cancers of the tongue, the rate has gone up. In 1995, there were fewer than 6,000 cases of tongue cancer. By 2005, that number was more than 8,000, according to the study.
Previous research has found that up to 50 percent of nonsmokers with throat and mouth cancers were infected with HPV, according to the study.
How people get infected hasn't been proven, but experts suspect oral sex may be the cause.
If that's the case, then the introduction of the cervical cancer vaccine for girls and women, which covers the common strains of HPV, may also help reduce the incidence of some head and neck cancers.
"We encourage the rapid study of the efficacy and safety of these vaccines in males and, if successful, the recommendation of vaccination in young adult and adolescent males," the study authors wrote.
"This gives us a good explanation of what we're seeing clinically," said Dr. Jay Brooks, chairman of hematology/oncology at Ochsner Health System in Baton Rouge, La. "Engaging in oral sex probably is the mode of transmission."
Both Brooks and Sturgis said that quitting smoking and drinking alcohol in moderation are still good ways to prevent head and neck cancers but that cutting down on those two risk factors may not be enough.
"We always thought, to prevent these cancers, all we had to do was get people to stop smoking and drinking excess alcohol, and stop chewing tobacco, and that we'd eliminate most head and neck cancers," said Sturgis. But, he added, future prevention efforts will likely focus on the HPV vaccine and on safe sex practices. For now, he said, women who've had an abnormal Pap smear and thei
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