WASHINGTON – The sexually transmitted virus that causes cervical cancer also sharply increases the risk of certain types of throat cancer among people infected through oral sex, according to a study being published today.
The study, involving 300 subjects with and without throat cancer, found that those infected with the human papillomavirus were 32 times more likely to develop one form of oral cancer than those free of the virus. Although previous research had indicated HPV caused oral cancer, the new study is the first to definitively establish the link, researchers said.
“It makes it absolutely clear that oral HPV infection is a risk factor,” said Maura Gillison, an assistant professor of oncology and epidemiology at the Johns Hopkins Medical Institutions in Baltimore, who led the study published in The New England Journal of Medicine.
The findings could help explain why oral cancer rates have been increasing in recent years, particularly among younger people and those who are not smokers or heavy drinkers, which had long been the primary at-risk groups, experts said.
“There’s been a kind of sea change in the last ten years in who we’re seeing with these cancers,” Gillison said. “It makes sense with some changes we’ve seen in sexual behavior.”
The findings provide new evidence that oral sex is not safe sex, despite widespread misconceptions to the contrary, particularly among adolescents.
“Many adolescents, and adults too, say they engage in oral sex as a less risky type of sex,” said Mark Schuster of the Rand Corp. and UCLA, noting that herpes, syphilis, gonorrhea, HIV and other sexually transmitted infections also spread through oral sex. “What this article and others show is you absolutely can get serious sexually transmitted diseases through oral sex.”
The findings could also provide new ammunition for those advocating wide use of a new vaccine that protects against HPV. Even though the vaccine has not been tested specifically to see if it reduces the risk of oral cancer, it is designed to protect against the type of HPV associated with the malignancy.
The study could also spur calls to vaccinate both boys and girls because oral cancer strikes both.
“This will reinvigorate and shift the debate about who should get vaccinated,” said Robert Haddad of the Dana Farber Cancer Institute in Boston.
Proponents of the vaccine have been advocating mandatory vaccination of girls, sparking an intense nationwide debate. Opponents say the vaccine may encourage sexual activity and that the vaccine is too new to know for sure that it is safe and its effectiveness is long lasting. They argue that the decision should be left to individual parents.
Regardless of whether they were infected, anyone who had had between one and five oral sex partners were 3.8 times more likely to have the cancer, whereas those who had more than six oral sex partners were 8.6 times more likely. It made no difference whether the partner was male or female.
It remains unclear whether kissing someone who is HPV-positive poses any risks, but “it is not out of the realm of possibility,” Gillison said.
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