MOUTH and throat infections of human papillomavirus (HPV), the most common sexually transmitted disease which can lead to cancer, are more common among men than women, said a United States study on Thursday.
Almost seven per cent of the US population age 14-69 has oral HPV with a prevalence rate of 10.1 per cent among men and 3.6 per cent among women, said the research in the Journal of the American Medical Association.
The findings shed more light on a growing epidemic of HPV-linked head and neck cancers which are expected to eclipse cervical cancer cases by 2020, and could warrant clinical trials of an HPV vaccine against oral lesions, the study authors said.
Currently the HPV vaccine is recommended for girls and boys as early as age nine and 10 to prevent cervical and anal cancers and genital warts.
The study included 5,579 people who took part in the National Health and Nutrition Examination Survey 2009-2010, and who agreed to a 30-second oral rinse test at a mobile examination centre.
Oral HPV was found to be more prevalent among people who had more lifetime or recent sex partners, and was also more frequent in current smokers, heavy alcohol drinkers and among former and current marijuana users.
Peak rates of oral HPV among men were seen at age 60-64, with 11.4 per cent of cases in that age range. The next highest oral HPV prevalence was seen in men age 30-34.
According to lead author Maura Gillison of the Ohio State University Comprehensive Cancer Centre, the data suggests that sex -- not casual contact or kissing -- is likely the cause of the oral HPV infections that researchers saw.
Oral cancers have "significantly increased over the last three decades in several countries and HPV has been directly implicated as the underlying cause," according to background information in the article.
Gillison, who has been studying HPV and cancer for 15 years, told a US science conference last year that when comparing people who have oral HPV to those who do not, "the single greatest factor is the number of partners on whom the person has performed oral sex."
People with oral HPV infections are 50 times more likely to get oral cancer than people who do not have HPV.
According to the Centres for Disease Control and Prevention, HPV is so common that 50 per cent of people who have sex will get it at some point in their lives.
While as many as 100 strains of HPV exist, most are cleared by the body on its own, though a handful can linger and lead to cancer.
About one per cent of the population is believed to carry HPV 16, which is linked to 85 per cent of HPV-related head and neck cancers.
Researchers have found a 225-per cent increase in oral cancer cases in the United States from 1974 to 2007, mainly among white men.
HPV is linked to almost 13,000 cases of cervical cancer yearly in US women, 4,300 of which are fatal. Researchers expect the number of oral cancer cases will surpass the number of cervical cancer cases in the next eight years.
The study was funded in part by the pharmaceutical giant Merck, which makes a vaccine against HPV.
Merck's Gardasil was approved for girls and women from age nine to 26 in June 2006 and for males in the same age range in October 2009.