(CBS/AP) Does oral sex explain the rise in the number of throat cancer cases among men?
A new report showed the HPV virus is fueling a 28 percent raise in orpharyngeal cancer cases since 1988 - an additional 10,000 cases per year.
If that trend continues, this type of upper throat cancer will surpass cervical cancer as the nation's main HPV-related cancer within 10 years, researchers from Ohio State University and the National Cancer Institute announced Monday.
"There is an urgency to try to figure out how to prevent this," said Dr. Amy Chen of the American Cancer Society.
While women can also get oral cancer caused by HPV, the risk is greater and rising among men, researchers said in the report, but they aren't sure why.
For the study - published in the Oct. 3 issue of the Journal of Clinical Oncology - researchers tested tumor tissue from 271 patients that had been stored in Hawaii, Iowa and Los Angeles. The proportion that were HPV-positive rose from 16 percent in the late 1980s to nearly 73 percent by the early 2000s.
Translate that to the overall population, and the researchers concluded that incidence rates of the HPV-positive tumors more than tripled while HPV-negative tumors dropped by half.
Previously, tobacco and alcohol use had been the main causes of these tumors, which occur in the tonsils, base of the tongue and upper throat. But over the past few years, studies have shown HPV is playing a role in these cancer rates, likely due to an increase in oral sex even as tobacco use has fallen.
While HPV is the most common sexually transmitted disease, studies show women's bodies usually clear the virus from the cervix quickly; only an infection that persists for years is a cancer risk. It's not known if oral HPV acts in a similar way, nor is it clear if oral sex is the only way it's transmitted, said Dr. Gregory Masters of the American Society for Clinical Oncology.
Regardless, more than 11,000 cervical cancer cases will be diagnosed this year, a number that has been dropping steadily thanks to better Pap smears. The researchers calculated that annual cases of cervical cancer will drop to 7,700 by 2020 - compared with about 8,700 cases of HPV-positive oropharyngeal cancer - about 7,400 of them in men.
The report raises the question: Can the vaccine that's currently given to young women protect men against oral HIV?
HPV vaccination is approved for boys to prevent genital warts and anal cancer, additional problems caused by human papillomavirus. But protection against oral HPV hasn't been studied in either gender, said report author Dr. Maura Gillison, a head-and-neck cancer specialist at Ohio State.
A spokeswoman for Merck & Co., maker of the HPV vaccine Gardasil, said the company has no plans to study the vaccine on oral cancer.
Regardless, the cancer society's Chen said the report suggests that patients with HPV-linked oral tumors have better survival odds than those with other types of this cancer, possibly because they tend to be younger.
Have a sore throat that lasts longer than two weeks? See a doctor, Chen cautioned:
"Just because you're not a smoker or drinker doesn't mean you can't get throat cancer."