Oral sex is no longer the safest way in getting or giving pleasure, it is also now one of the leading causes of oral cancer, according to a study done by American scientists. Studies made by the Ohio State University from the years 1974 to 2007, showed a 225 percent increase in oral cancer cases in the United States linking the incurable human papillomaviruses (HPV) as primary culprits. The study further claims that the more a person had oral sex engaged with six o world r more partners over a lifetime the higher the risk that he or she could get an HPV-related cancer. "When you compare people who have an oral infection or not," said Maura Gillison, "the single greatest factor is the number of partners on whom the person has performed oral sex." "When the number of partners increases, the risk increases," she told reporters at the American Association for the Advancement of Science meeting in Washington. Gillison has been studying HPV and cancer for 15 years. According to a related report by Agence France Presse, further study should be conducted as oral cancer due to HPV infection is now more common than oral cancer from tobacco use, which remains the leading cause of such cancers worldwide. Previous studies have suggested that people who have performed oral sex on six or more different partners over a lifetime face an eight-fold higher risk of acquiring HPV-related head or neck cancer, she said. But even though the link between HPV and cervical cancer has been well known for many years, and vaccines now exist to provide some protection for young women, much study remains to be done, Gillison said. "The cervical cancer field is 20 years ahead," she said. "We can't demonstrate definitively that certain behaviors are associated with risk of acquiring an infection," she said. "The rise in oral cancer in the US in predominantly among young white males and we do not know the answer as to why."