A virus known to cause cervical cancer in women is increasingly being identified in head and neck cancers, leading to suspicion that the route of infection may be oral sex.
Human papillomavirus, or HPV, is often associated with genital warts and cervical cancer, but the virus can cause numerous other forms of cancer. Doctors who treat head and neck cancers are increasingly concerned that sexual encounters among young adults may be driving more oral cancers later in life.
"A third of head and neck cancers we see nowadays are HPV," said Dr. David Brizel, an oncologist at Duke University who specializes in head and neck cancers.
Although few studies have been done to establish a direct cause and effect, public health officials cite oral sex as a means of infection in both men and women.
In recent months, several studies in both European and U.S. medical journals have noted a rise in head and neck cancers stemming from HPV infections.
A 2007 study published in The New England Journal of Medicine correlated oral HPV cancers to a high number of oral sex partners.
Earlier studies noted an increased incidence of head and neck cancers among the husbands of women diagnosed with HPV-based cervical cancers.
Brizel said smoking and drinking are typically the biggest risk factors for head and neck cancers, but the increases in the HPV-related tumors have occurred as smoking rates have declined in the United States.
"That's worth noting," he said. "A large portion of these are in people who never used tobacco. I saw one (patient) last week, and the week before that, who never touched a cigarette."
Dr. Peter Cartwright, a gynecologic specialist at Duke, said he's not convinced that oral sex is the cause of rising HPV head and neck cancers. He said the virus is ubiquitous -- most everyone picks it up at some time, with no lasting harm -- and it could also be spread on hands, eating utensils or other items.
"Are you saying that oral sex is more common now than 30 years ago?" he asked. "I don't think so."
Behavioral studies conducted by the Guttmacher Institute, which focuses on reproductive health, support Cartwright's suspicion. Rebecca Wind, spokeswoman for the group, said researchers have found no uptick in oral sex activity in recent decades.
A federal survery of sexual behaviors conducted earlier this decade showed that 90 percent of U.S. men between the ages of 25 and 44 had engaged in oral sex with an opposite-sex partner, and 88 percent of women in those age groups had had oral sex.
But there may be hints in the 2007 New England Journal of Medicine study. While more people may not engage in oral sex, they may have more partners -- and at earlier ages. The journal's authors found that people who had at least six different oral sex partners were at higher risk of developing HPV-related head and neck cancers.
"The widespread oral sexual practices among adolescents may be a contributing factor in this increase," the study's authors wrote.
It's also not yet known how the HPV vaccine might affect the rates of head and neck cancers. The first HPV vaccine, Gardasil, was approved in 2006 to thwart cervical cancer, and has been recommended for young women before they become sexually active.
Some health leaders have suggested that men, too, should be vaccinated.
Brizel said that approach may be too expensive and unnecessary if enough women are inoculated against the virus.
"From a public health standpoint, there are lots of other things to vaccinate against -- polio, flu, etc.," he said.
Brizel said HPV-related head and neck cancers respond better to treatment than other such cancers. He said patients who don't have a recurrence of cancer after two or three years are generally considered cured.
ABOUT HPV-RELATED CANCERS
What is it? Human Papillomavirus is actually a group of over 100 different viruses, with at least 30 strains known to cause different types of cancer.
How do you get it? It's spread by skin-to-skin contact and thrives in warm, moist tissue.
What are the symptoms? The types of HPV that can cause genital warts are not the same strains that can cause cancer. There is no way to know which people who get HPV will go on to develop cancer or other health problems. Cervical cancer usually does not have symptoms until it is quite advanced, and other HPV-related cancers might also advance without signs or symptoms. These include cancers of the vulva, vagina, penis, anus, and head and neck.
Explore further: Colon cancer: Taking a step back to move forward