How Does Oral Sex Cause Cancer? Michael Douglas Blames Cunnilingus For Diagnosis

Actor Michael Douglas survived a very near brush with death when he overcame throat cancer after being diagnosed as Stage 4 in 2010, and beat it over the last couple of years.

It was a tale of will and medicine triumphing over disease, and many immediately blamed the cancer on his storied drinking and smoking.

But Douglas made the surprising admission in an interview with the Guardian on Sunday that the cancer actually stemmed from a less-obvious source, namely human papillomavirus contracted via oral sex.

“Without wanting to get too specific, this particular cancer is caused by HPV, which actually comes about from cunnilingus,” Douglas, 68, told the British newspaper. "I did worry if the stress caused by my son's incarceration didn't help trigger it. But yeah, it's a sexually transmitted disease that causes cancer. And if you have it, cunnilingus is also the best cure for it."

The revelation started people's tongues wagging about Douglas' personal life, but it also made many people wonder (or worry) about the connection between oral sex and oral cancer. So let's take a look at that.

There are 150 viruses that fall under the category of HPV, more than 40 of which can be spread via vaginal, anal and, yes, oral sex, according to a study by the Centers for Disease Control and Prevention.

The viruses are so common that more than 50 percent of sexually active people contract one or more strains of it during the course of their lives -- a fact that has become common (and cringe-worthy) knowledge due to sex-ed classes and public education campaigns.

But people with HPV needn't all go running to an oncologist just yet, as only about 12 HPVs are known to be oncogenic, or cancer-causing, and of those HPV types, 16 and 18 lead to the majority of HPV-related cancer.

Still, it's a pretty serious scourge on public health, as the National Cancer Institute reports that about 5 percent of cancers worldwide stem from "high-risk HPV infection," though "most high-risk HPV infections occur without any symptoms, go away within 1 to 2 years, and do not cause cancer," according to the National Cancer Institute.

A range of different cancers can be caused by HPV infections, including "virtually all cervical cancers," anal, vaginal, vulvar, penile cancers and "cancer of the oropharynx, which is the middle of the throat containing the soft palate, the base of the tongue and the tonsils," the National Cancer Institute writes.

Despite the fact that Douglas claims his cancer was caused by HPV, the institute also notes that smoking can increase the risk of HPV-related cancer.

HPVs work by infecting epithelial cells, which are arranged in layers on the inner and outer surfaces of the body from the skin to the throat to the anus. After infecting these cells, an HPV produces proteins, some of which can disrupt cell function and cause it to grow unabated in order to keep cells alive, the National Cancer Institute explains.

Often the infected cells are eliminated by the immune system, but they sometimes continue to grow, eventually building into a tumor over a period of as long as two decades.

It's a long road from getting an HPV infection to possibly contracting cancer, but it is one that about 7,100 unfortunately complete each year, the Centers for Disease Control and Prevention reports.

So, as always, do try to be careful when engaging in any sexual activity, especially with new partners.