One of the studies conducted at the Johns Hopkins University monitored 1,670 patients with oral cancer and 1,732 healthy people without the cancer. They found that the human papilloma virus, which is implicated in the development of oral cancer, was found in a small percentage of the patients who had cancer. It was not found in healthy patients. Among the patients who did have the virus, the HPV16 strain was the most prevalent one. This particular strain has been found to affect one-fifth of women aged between 18 and 25 in some studies in Britain. The Johns Hopkins study found that people whose mouth tumors had the HPV16 strain were three times as likely to have had oral sex as those who did not have the virus.
In a separate study, Swedish researchers at the Malmo University Faculty of Odontology, observed 132 patients with mouth cancer and compared their viral profiles with 320 healthy people. It was found that 36 percent of the cancer patients were harboring the HPV as compared to only 1 percent of the control group. "You should avoid having oral sex," said the dentist and researcher Kerstin Rosenquist, and lead author of the study at the Malmo University's Faculty of Odontology in southern Sweden. The human papilloma virus is of 40 types and has been associated with genital warts as well as cancer of the cervix or anus and now oral or mouth cancer. Oral cancer is usually caused by smoking, chewing tobacco as well as consuming excess alcohol.