Check Up: Michael Douglas' frank revelation was a teachable moment

It's not every day that a movie star says "cancer" and "cunnilingus" to a reporter, so Michael Douglas probably should have known his frankness would become fodder for bloggers, tweeters, and late-night comics.

In any case, his revelation last week that his throat cancer was caused by a sexually transmitted virus can serve as a teachable moment - which is what he later said was his aim in the Guardian interview.

Human papillomavirus, or HPV, is a family of more than 100 virus types that can live in the flat, thin cells on the surface of the skin, cervix, vagina, anus, vulva, penis, mouth, and throat.

The virus is spread through contact with infected skin, mucous membranes, and bodily fluids. So, some types can be passed during intercourse or - as Douglas noted - oral sex.

Most infections are wiped out by the immune system without so much as a symptom. But certain types of HPV can produce warts on the skin, genitals, or in the throat. And 14 "high-risk" types are known to cause cancer.

The most common HPV-related cancer develops in the cervix, usually after years of precancerous changes. That's why the low-tech Pap smear is effective; detecting and removing the abnormal cells prevents cancer.

These dangerous HPV types also give rise to some cancers of the genitals, head, and throat. Pathologists find the culprit by analyzing a tumor sample.

In recent years, HPV- related head and throat cancers have increased, but the numbers are still small.

"They're called oropharyngeal cancers," said Miriam N. Lango, a head and neck surgeon at Fox Chase Cancer Center. "They're very rare, about 7,000 new cases a year." For unknown reasons, men make up about 85 percent of those cases, she said.

One thing that is known - although apparently not to Douglas - is that smoking and drinking can promote malignant changes in HPV-infected cells. Lango said the resulting cancer also tended to be more aggressive.

In the Guardian story, published last week to coincide with Douglas' portrayal of Liberace in the HBO movie Behind the Candelabra, he was asked whether he rued his years of smoking and drinking, which he initially blamed for his throat cancer.

"No, no," Douglas was quoted as saying. "Because without wanting to get too specific, this particular cancer is caused by HPV, which actually comes about from cunnilingus."

The good news is that Douglas, 68, has been cancer-free for more than two years. Meanwhile, vaccines have been approved to ward off two types of HPV that cause the most cancer. Experts recommend Merck's Gardasil for boys and girls, and GSK's Cervarix for girls.

They may have found a new spokesman. Explaining his candor, Douglas said: "I simply, to a reporter, tried to give a little PSA announcement about HPV, a virus that can cause oral cancer, and is one of the few areas of cancer that can be controlled, and there are vaccinations that kids can get."