Oral sex is now the main cause of throat cancer

The 'main risk factor' is the number of partners someone has had oral sex with

It is now more common than cervical cancer in the UK and US, an expert has said.

Much of this is due to one particular type of throat cancer - oropharyngeal cancer - which affects the area of the tonsils and back of the throat and is due to the human papillomavirus (HPV). HPV is also the main cause of cancer of the cervix.

HPV is the name of a very common group of viruses, according to the NHS. It states that "they do not cause any problems in most people, but some types can cause genital warts or cancer. HPV affects the skin". There are more than 100 different types.

Dr Hisham Mehanna, from the UK’s University of Birmingham, said people with multiple oral sex partners were more than eight times more likely to develop the cancer.

Writing in The Conversation, Dr Mehanna said: “Over the past two decades, there has been a rapid increase in throat cancer in the West, to the extent that some have called it an epidemic.

Medical experts have pegged HPV infection to be the biggest risk factor for developing the disease.

"The prevailing theory is that most of us catch HPV infections and are able to clear them completely," Mehanna writes.

"However, a small number of people are not able to get rid of the infection, maybe due to a defect in a particular aspect of their immune system. In those patients, the virus is able to replicate continuously, and over time integrates at random positions into the host’s DNA, some of which can cause the host cells to become cancerous."

Dr Mehanna said, for oropharyngeal cancer, the "main risk factor" is the number of partners someone has had oral sex with.

“Those with six or more lifetime oral-sex partners are 8.5 times more likely to develop oropharyngeal cancer than those who do not practice oral sex," he wrote.

In the UK, 80 per cent of adults reported practising oral sex at some point in their lives, Mehanna's report states.

"Yet, mercifully," he assures, "only a small number of those people develop oropharyngeal cancer."

According to the NHS, around 8,300 people are diagnosed with throat cancer each year in the UK, which is about 1 in every 50 cancers caught. More than 2 in 3 cases of mouth cancer develop in adults over the age of 55. Only 1 in 8 (12.5 per cent) happens in people younger than 50.

Doctors say that oral sex is the biggest risk factor for developing oropharyngeal cancer— more than from smoking, alcohol consumption, and an unhealthy diet.

HPV is a common virus spread through vaginal, anal and oral sex with someone who is already infected.

There is a vaccine, which is more than 80 per cent effective, and widely available.

According to previous government data, HPV vaccine coverage in England for girls completing a 2-dose HPV schedule by Year 9 is 67.3 per cent. In boys, 62.4 per cent are double vaccinated.

Hollywood actor Michael Douglas revealed in 2013 that his cancer was caused by oral sex.