In the United States, oral cancer due to HPV infection is now more common than oral cancer from tobacco use, which remains the leading cause of such cancers in the rest of the world.
Researchers had found a 225 per cent increase in oral cancer cases in the US from 1974 to 2007, mainly among white men, said Maura Gillison of Ohio State University.
"When you compare people who have an oral infection or not ... the single greatest factor is the number of partners on whom the person has performed oral sex," said Gillison, who has been researching HPV and cancer for 15 years.
"When the number of partners increases, the risk increases."
Previous studies have suggested that people who have performed oral sex on six or more partners over a lifetime face an eight-fold higher risk of acquiring HPV-related head or neck cancer than those with fewer than six partners, she said.
There as many as 150 different types of human papillomaviruses, and about 40 of those can be sexually transmitted. Some may cause genital warts, while other more high-risk varieties can cause oral, anal, vaginal and penile cancers.
Sexually transmitted HPV infections are common and often asymptomatic, and untreated cases in women are the main cause of cervical cancer.
A study published earlier this month in the New England Journal of Medicine found that the HPV vaccine could prevent 90 per cent of genital warts in men, and the vaccine has also been approved against anal cancer in men and women.
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