Oral sex dramatically increases the risk of head and cancers, a new study has claimed.

The disease has traditionally been considered to be one that affects smokers and heavy drinkers in later life.

But over recent years, as cases have been rising, it has been linked with the common human papillomavirus (HPV).

It is believed oral sex may be the main way (HPV) - more usually associated with cervical cancer - ends up in the mouth.

The group of viruses affect the skin and moist membranes which line the body, including the anus, cervix and mouth and throat.

HPV-16 is a well-known cause of oropharyngeal tumours - those which affect the middle part of the throat including the soft palate, the base of the tongue and the tonsils. 

This new study, published in the journal JAMA Oncology, is the first to show conclusively that HPV-16's presence in the mouth leads to the development of oropharyngeal cancer.