Oral sex with multiple partners and oral infection with human papilloma virus are the strongest risk factors for cancers of the mouth and throat, far outweighing the contribution of alcohol and tobacco, researchers from the Johns Hopkins University Kimmel Cancer Center report in the May 10 th issue of the New England Journal of Medicine. Oral cancers have in the past been blamed on heavy smoking and drinking, and an infectious cause has been debated. Some strains of this virus cause warts, including genital and anal warts. Other strains are responsible for cervical cancer, anal cancer and some cancers of the penis, vagina, vulva, urethra, tongue and tonsils. Kissing, licking or sucking another person's genitals, i.