Oral HPV affects more men than women in the U.S.

Roughly one in nine U.S. men hasan oralinfectionof the cancer-causing human papillomavirus (HPV),more than triple the infection rate for women, a new studysuggests.

HPV is among the most common sexually transmitted diseases.Most infectionsdon't cause symptoms and go away on their own.

But the virus can cause cancers of the throat, anus, penis,cervix, vagina and vulva, as well as genital warts and lesionsin the upper respiratory tract.

Among U.S. adults ages 18 to 69, approximately 11 millionmen and 3.2 million womenhave oral HPV infections,researchers estimates. Men were at the highest risk ofdeveloping oral HPV when they had oral sex with other men oralso had genital HPV infections.

Rising rates of HPV infections among men may help explainwhy throat cancers in them are now more common than cervicalcancer in women, said senior study author Ashish Deshmukh, apublic health researcher at the University of Florida inGainesville.

• Cases of HPV-related oral cancers have risen significantly in Canada, study finds

"We have the HPV vaccine approved for use in both boys andgirls, which has the potential to decrease rates ofHPV-associated cancers in the future,"Deshmukh said by email. "But the low uptake of the vaccine among boys and disparities inthe uptake remains a concern."

In Canada, the proportion of oral cancers caused by the human papillomavirus has also increased, by about 50 per cent between 2000 and 2012, a study published in August suggests.

Statistics from a Canadian Cancer Society report last fall showed 1,335 Canadians were diagnosed in 2012 with HPV-related oropharyngeal cancer,and 372 died from the disease.

In the U.S., the HPV vaccine is recommended for childrenage 11 or 12, with the goal of protecting them against the virusbefore they become sexually active, and also for teens and youngadults who may not have previously been vaccinated.

No treatment exists for persistent infection

But as of last year, only about half of girls and even fewerboys got the two-dose series of shots needed to fully protectagainst the virus, Deshmukh said.

The most common cancer related to HPV infection is oropharyngeal squamous cell carcinoma (OPSCC), a typeof head and neck cancer that is disproportionately prevalent inmen, researchers note in the Annals of Internal Medicine.

It is critical that we maximize HPV vaccination rates inadolescents and young adults.-Dr. ErichSturgis

While the HPV vaccine may help prevent these tumours, thevaccine is currently only recommended for people up to age 26and many men are too old to receive the shots.

For the study, researchers examinednationally representative survey data from 4,493 men and 4,641women. They found that overall, 11.5 per cent of men and 3.2per cent of women had oral HPV infections.

A high-risk strain of the virus, HPV 16, was the cause oforal infections in 7.3 per cent of men and 1.4 per cent of women.But among those reporting same-sex sexual partners, 12.7 per cent of men and 3.4 per cent of women had high-risk infections.

Nearly 20 per cent of men with genital HPV infections alsohad oral HPV, compared to just over fourper cent of men withoutgenital HPV, the researchers also found.

One limitation of the study is that it relied on surveyparticipants to accurately report on their sexual orientationand behaviours and stigma might lead some people to beuntruthful, the authors note.

Still, the findings highlight a need for better preventionamong both men and women, said Dr. Erich Sturgis, a researcherat the University of Texas MD Anderson Cancer Center in Houstonwho wasn't involved in the study.

"We do not have treatment for persistent infection orscreening for many HPV-related cancers,"Sturgis said by email.

"It is critical that we maximize HPV vaccination rates inadolescents and young adults,"Sturgis added. "This cannot bestressed enough."

In addition to vaccination, condoms can also help lower therisk of HPV transmission, Deshmukh said. Men and women can bothget screened for anal cancer, and women can get cervical cancerscreenings to catch any tumors earlier when they may be easierto treat, he added.