9:53pm UK, Wednesday February 25, 2004

Scientists have uncovered evidence that oral sex can cause mouth cancer - although the risk is small and it is more likely to result from heavy drinking and smoking.

Researchers had suspected that a sexually transmitted infection that is linked to cervical cancer could also be associated with tumours in the mouth.

Now a study by researchers working for the International Agency for Research on Cancer in France seems to have confirmed it.

The scientists studied more than 1,600 patients from Europe, Canada, Australia, Cuba and the Sudan with oral cancer and more than 1,700 healthy people.

They found that patients with oral cancer containing a strain of the human papilloma virus (HPV) known as HPV16 were three times more likely to report having had oral sex than those without the virus strain.

High consumptions of alcohol and cigarettes are estimated to cause up to nine out of ten cases of oral cancer.

The combination of tobacco smoke and alcohol are thought to produce high levels of cancer causing agents.

Scientists are currently working on vaccines to prevent cervical cancer, which is more common, but they might also be effective against oral cancer.