An estimated 7 percent of American teens and adults, or 16 million, carry the human papilloma virus in their mouths, which puts them at heightened risk of developing cancer of the mouth and throat, researchers said Thursday.
Their study, the first to assess the prevalence of oral HPV infection in the U.S. population, may help health experts understand why rates of oropharyngeal cancer — a type of head and neck cancer — have increased by 225 percent between 1988 and 2004.
The findings also indicate that the virus is not likely to spread through kissing or casual contact and that most cases of oral HPV can be traced to oral sex.
"There is a strong association for sexual behavior, and that has important implications for public health officials who teach sexual education," said Dr. Maura L. Gillison of the Ohio State University Comprehensive Cancer Center, who led the study.
Gillison presented the data Thursday at a meeting of head and neck cancer researchers and doctors in Phoenix. The results were also published online by the Journal of the American Medical Association.
HPV is best known as the cause of cervical cancer, which kills 4,220 women in the United States each year, according to the National Cancer Institute. The virus can also cause vulvar, anal, penile and various head and neck cancers. A study published in October in the Journal of Clinical Oncology traced more than 70 percent of new cases of oral cancers to HPV infection, putting it ahead of tobacco use as the leading cause of such cancers.
If present trends continue, HPV will cause more cases of oral cancers than cervical cancer by 2020, according to the October study.
HPV infection is common — an estimated 80 percent of Americans have contracted the virus, Gillison said. It usually produces no symptoms and is typically cleared from the body through natural processes.
But persistent infections can cause cancer. Vaccines are now available for children and young adults to prevent cervical and anal cancers caused by the most troublesome HPV strains.