HPV linked to throat cancer; oral sex ups risk

Human papillomavirus (HPV) causes some throat cancers in both men and women, says a new study in TheNew England Journal of Medicine. And having multiple oral sex partners tops the list of sex practices that boost risk for the HPV-linked cancer.

"People should be reassured that oropharyngeal cancer is relatively uncommon, and the overwhelming majority of people with an oral HPV infection probably will not get throat cancer," said study author Maura Gillison, an assistant professor of oncology and epidemiology at Johns Hopkins University, in a release. Consistent condom use may reduce risk.

In Gillison’s study of 100 men and women newly diagnosed with oropharyngeal cancer (located on the tonsils, back of the tongue, and throat) and 200 control patients without cancer, those who had evidence of prior HPV infection were 32 times more likely to have developed the cancer. This was much higher than the rate for smokers (three times) and drinkers (two times). Study participants who reported having more than six oral sex partners during their lifetime were 8.6 times more likely to develop the HPV-linked cancer. In a surprising twist, Gillison said the data showed no added risk for HPV carriers who smoke and drink alcohol. "It’s the virus that drives the cancer," explained Gillison. "Since HPV has already disrupted the cell enough to steer its change to cancer, then tobacco and alcohol use may have no further impact."

Oral sex, including both fellatio and cunnilingus, is the main mode of transit for oral HPV infection, the investigators say, although mouth-to-mouth transmission remains possible and was not ruled out by the current study.

HPVs also can be transmitted by skin contact and are found in the mucus of the genital tract, and in saliva, urine, and semen. Both men and women contract the virus—which is believed to infect a large percentage of people worldwide at some point in their lives—in equal numbers. Most HPV infections pass with few or no symptoms, but a small percentage of men and women who acquire cancer-causing or "high-risk" strains, such as HPV 16, may develop a cancer. HPV-linked cancers currently include oral, anal, cervical, vaginal, penile, and vulvar cancers.

Gillison noted that the new FDA-approved vaccine known by the trade name Gardasil can prevent genital HPV infections in girls and young women but has not yet been shown to prevent infection in boys and men. Nor is it known whether the vaccine can prevent oral HPV infections and oral cancers, which are more common in men. (The Advocate)