By Maria Cendejas

A study in the Journal of the American Medical Association, oral infections with HPV are more common than doctors expected, according to USAtoday.

Infections with human papilloma virus( HPV) heightens the risk of developing cancer of the mouth and throat. The findings indicate that most cases of oral HPV can be traced to oral sex, rather than kissing or casual contact, says study author Maura Gillison, a professor at the Ohio State University Comprehensive Cancer Center.

Gillison found in the new study of 5,579 Americans from ages of 14-69 that 7% of Americans have an oral infection with HPV. That's higher than she expected. Her study provides the first major estimate of oral HPV infection rates for the whole country.

According to the study conducted as part of the Centers for Disease Control and Prevention (CDC)'s 2009-10 National Health and Nutrition Examination Survey, oral HPV infection in men is nearly 3 times as common in women, affecting 10.1% of them, but only 3.6% of women. 

Gillison says the study doesn't explain why HPV infection is more common in men. 

The doctors have determined that throat cancers are far more common in men than in women suggesting that HPV infections may be part of the risk for the malignancy.

While some throat cancers are caused by HPV, others are linked to smoking and drinking alcohol, which is a known cancer-causing agent, according to the National Toxicology Program.

Gillison published that study in October showing that the percentage of HPV-related throat cancers went up from 16% in 1984-1988 to 72% in 2000-04.

According to the CDC, about 12,200 women are diagnosed with cervical cancer each year, while about 7,100 people develop HPV-related throat cancer annually. 

Gillson said,“If it continues by 2020, throat cancers will overtake cervical cancers as the leading cause of HPV-related tumor.”

While doctors have a clear understanding of HPV's path from infection to cancer of the cervix, they know little about how the virus infects the throat and what allows it to progress to cancer. The studies show that about 42% of women have an existing genital HPV infection. By the age of 50 about 80% of women are infected with HPV, she says.

Kevin Ault, who is an obstetrician/gynecologist at Atlanta's Emory University School of Medicine, and wasn't involved in the new study, said,“ Nearly everyone who is sexually active will get a genital infection with HPV. However, I am not sure we know that about HPV and oral infections."

Gillison says she was surprised that oral infections were so common.

The infections were also clearly linked to sex. Oral HPV infections were 8 times more common among people who have had sex — defined as vaginal, oral or anal intercourse — than those who have never had sex, Gillison says. 

The infections were more common in people who had more sex partners and who began having oral sex when they were teenagers. Less than 1% of people without sexual experience had an oral HPV infection.

For the parents who are worried that their teens might spread HPV through kissing, Gillison says, it is important for people to teach sexual health and wellness. The study also revealed that smoking increases the risk of a current infection. It is possible that smoking leaves the body more vulnerable to infection or makes infections more difficult to be cleared.

In an accompanying editorial, Drexel University's Hans Schlecht says doctors should counsel patients who have oral sex to use barrier protection, such as a condom or other device. An infectious-disease specialist, Schlecht says doctors also should look out for early signs and symptoms of throat cancer. While doctors can screen for cervical cancers, detecting and removing them in precancerous stages is important because doctors have no way to screen for throat cancer, which can cause unexplained weight loss, earache, difficulty speaking, difficulty swallowing or a feeling of a lump in the throat, Schlecht writes.

The Food and Drug Administration has approved 2 vaccines that prevent HPV infection, which accounts for a majority of cervical cancer. The vaccines also protect against vaginal, vulvar and anal cancers. In last fall, the CDC advisory panel suggested giving the vaccines to all children at age 11 or 12.  

However, studies did not consider cancer cases as outcomes of the trial.  Instead, trials only considered the surrogates (HVP lesions, which indicate risk of cancer) as evidence that the vaccine can reduce the risk of cervical cancer, according to a health observer.

Gillison says these vaccines cost about $360 for three shots, and it hasn't been tested on throat cancer.

Given the benefits of preventing cancer, however, Ault says the study "does argue for vaccinating everyone." And, he says, it adds "yet another reason not to smoke."