About 10 percent of men and 3.6 percent of women are orally infected with human papillomavirus, which is acquired through oral sex and can cause cancer.
There are two peaks in the age people are infected -- 30 to 34 and 60 to 64, according to the study published today in the Journal of the American Medical Association. The virus is linked to throat cancer, and is becoming a more common cause of the disease as Americans quit smoking.
The virus, called HPV, is the most-common sexually transmitted virus in the U.S., where half the population will be infected at some time in their lives, according to the Centers for Disease Control and Prevention. It is known to cause cervical, vulvar, vaginal, penile and anal cancer. The higher HPV infection rate in men explains why their head and neck cancer rates are greater, said Maura Gillison, a professor at the Ohio State University College of Medicine in Columbus.
“This provides pretty strong evidence that the higher infection rate is the reason why,” said Gillison, the study’s lead author, in a telephone interview. “This is a jumping board for additional research.”
Besides sex, other demographics associated with oral HPV infection include age, lifetime number of sex partners, and the number of cigarettes smoked each day.
The research is the first population-based study to examine how many men and women were infected, Gillison said.
Though Merck & Co.’s Gardasil and GlaxoSmithKline Plc’s Cervarix target genital HPV, it’s unknown whether the vaccines will protect against oral infections as well.
Gardasil is approved for preventing cervical, vaginal and anal cancers and genital warts, and is recommended for girls and women 9 to 26 years old. It’s also approved for genital warts and anal cancer in boys and men of the same ages. Cervarix is approved for preventing cervical cancer in females 9 to 25.
In places like Australia, where 80 percent of girls have been vaccinated, the lowered prevalence of the virus may be enough to protect men against oral HPV infection, Gillison said. Further research needs to be done to see if vaccination will help lower oral HPV infection rates, she said. Not enough people in the U.S. are vaccinated to get a benefit, she said.
“We have a cancer that occurs largely among men and there’s no screening or preventive strategy,” Gillison said. It’s difficult to sample the site in the throat where the virus makes its home, she said.
Among the 2,483 men who participated in the study conducted in 2009 and 2010, 264 had an oral HPV infection. Of the 2,385 women, 88 had an oral infection, the study showed.
The infection was contracted by about 7 percent of those ages 30 to 34 and 11 percent of those 60 to 64, according to the study.