By Dr Ananya Mandal, MD
A new study suggested that an estimated 7% of American teens and adults carry the human papillomavirus in their mouths. This may help health experts finally understand why rates of mouth and throat cancer have been climbing for nearly 25 years. The evidence additionally makes it clear that oral sex practices play a key role in transmission.
This was reported online Thursday by the Journal of the American Medical Assn. and is the first to assess the prevalence of oral HPV infection in the U.S. population. The findings 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 and presented the findings Thursday at a meeting of head and neck cancer researchers and doctors in Phoenix.
Experts say that although herpes, HIV and other diseases can be transmitted via oral sex, the practice is often considered a safer alternative to sexual intercourse. A survey released last year by the U.S. Centers for Disease Control and Prevention found that about 90% of adults have had oral sex, along with 27% of 15-year-old boys and 23% of 15-year-old girls.
“I don't think people think of oral sex in the same way they do with traditional intercourse,” said Fred Wyand, director of the HPV Resource Center at the American Social Health Assn. in Research Triangle Park, N.C. “Sometimes younger people engage in oral sex so they don't have to worry about pregnancy. They may not even make the link between oral sex and STDs.”
However the link between oral cancers and transmission of HPV to the mouth has been mounting over the last decade. Initial studies found that patients with oral cancer were far more likely than healthy controls to have engaged in oral sex. And a 2007 study in the New England Journal of Medicine found that the more oral sex partners a person has had, the greater their risk of developing throat cancer.
HPV is best known as the cause of cervical cancer, which kills 4,220 women in the U.S. 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% of new cases of oral cancers to HPV infection, putting it ahead of tobacco use as the leading cause of such cancers.
Most oral HPV infections are harmless, and oral cancers are still relatively uncommon. But given the new information, doctors should encourage their patients to use protection during oral sex, Dr. Hans Schlecht, assistant professor of medicine at Drexel University College of Medicine in Philadelphia, wrote in an editorial accompanying the study. “It's something people are not comfortable talking about, but it is protective,” he said in an interview. “If you are going to be intimate with someone, there are some adult conversations you need to have.”
HPV infection is common — an estimated 80% 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.
For this new study Gillison and her colleagues analyzed data from 5,579 people ages 14 to 69 who participated in the National Health and Nutrition Examination Survey in 2009 and 2010. The survey includes a detailed questionnaire and a physical examination, including the first large-scale use of a 30-second oral rinse from which researchers were able to extract cells to test for HPV infection.