http://www.channel4.com/news/article...+cancer/508662

Oral sex can raise the risk of throat cancer by transmitting a virus linked to the disease, scientists have claimed.Study participants who had more than six oral sex partners in their lifetime and evidence of HPV infection were 8.6 times more likely to develop the cancer than those who had never engaged in oral sex.

The possibility of mouth-to-mouth transmission of the virus, for instance by kissing, could not be ruled out, said the researchers. HPV can be passed on by skin contact and may be found in the genital tract, the saliva, urine and semen.