Can Oral Sex Cause Throat Cancer?

Michael Douglas was diagnosed with throat cancer (oropharyngeal cancer) three years ago. He initially said it was caused by years of heavy smoking, alcohol abuse and stress. However, he recently told The Guardian newspaper that it was caused by oral sex .
What is HPV, and what are the risks?
Human papillomavirus is an infection that causes genital warts. They are the second most common type of sexually transmitted infection after chlamydia.
Genital warts typically appears on the in the female and male urogenital tract.

In most cases, genital HPV infections cause no real symptoms and clear up by themselves without causing any problems.

HPV comes in more than 100 different strains and some can trigger cancers.
Most cases of genital warts are caused by 'low-risk' HPV types 6 and 11, meaning they do not pose a significant cancer risk.
High-risk types include HPV 16 and 18 which can cause cancer of the cervix in women.
High-risk HPV infections are also associated with cancer of the penis, vulva, vagina, anus, mouth and throat.

How is HPV spread?

Genital warts can be spread during vaginal or anal sex, and by sharing sex toys. However, you do not need to have penetrative sex to pass the infection on because HPV is spread by skin-to-skin contact.
HPV infection can also be spread through oral sex.
It can take up to one year for warts to develop after infection with HPV. Therefore, if you are in a relationship and you get genital warts, it does not necessarily mean your partner has been having sex with other people.
HPV is most likely to be transmitted to others when warts are present, but it is still possible to pass the virus on before the warts have developed and after they have disappeared.
Condoms do not provide complete protection because it is possible for the skin around the genital area (not covered by the condom) to become infected.

So, what is the risk of developing throat cancer from oral sex?

In 2011, Gillison and her colleagues conducted a study looking at the proportion of oropharynx cancers associated with HPV over time in the U.S. The proportion increased from 16% to 72% from the late 1980s to the early 2000s. A While there's been a decrease in smoking-related head and neck cancers since the late 1980s, we've seen a steady increase in oropharyngeal cancers in the tonsil and base of tongue area that are caused by a strain of HPV, HPV Type 16, that can be transmitted through oral sex. But it doesn't mean that everyone who engages in oral sex is going to get this type of cancer. It's actually a small percentage of people who contract the virus and can't fight it off

Oral sex with 6 or more partners raises risk of throat cancer, said one study

In a study published in NEJM (New England Journal of Medicine), Dr Maura Gillison of Johns Hopkins Bloomberg School of Public Health in Baltimore, Maryland, USA, and team suggested that people who have oral sex with at least 6 different partners have a significantly have a higher risk of developing throat cancer  

The team recruited 100 patients who had recently been diagnosed with oropharyngeal cancer, as well as 200 "healthy" individuals (the control group).

They found that people who had at least 6 oral-sex partners during their lifetime were 3.4 times more likely to have throat cancer. Those with 26 or more vaginal-sex partners had a 3.1 times higher risk of developing throat cancer.

What are the risk factors for throat cancer?

Smoking - this is by far the most important risk factor for throat cancer. Regular, long-term, heavy smokers are 20 times more likely to develop some type of throat cancer compared to non-smokers.

Alcohol - heavy, chronic alcohol consumption, particularly spirits, also raises the risk of developing throat cancer.

People who do both - drink and smoke a lot - have the highest risk.