Michael Douglas Cancer HPV says oral sex caused his throat cancer. Not smoking!

In a surprisingly frank interview with the Guardian newspaper, actor Michael Douglas says that the throat cancer he was diagnosed with three years ago was caused by oral sex.

When asked by the Guardian if he regretted the years of smoking and drinking thought to be associated with his illness, the actor replied, "No. Because without wanting to get too specific, this particular cancer is caused by HPV [human papillomavirus], which actually comes about from cunnilingus."

Douglas, 68, went on to say in Sunday's story that he "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." Douglas has been married to actress Catherine Zeta-Jones since 2000.

A 2011 study detailed in the Journal of Clinical Oncology, and covered here by NBC News, showed that a cancer spike, mainly in men, was tied to HPV from oral sex.

Related: Michael Douglas is right - HPV can cause throat cancer

Douglas announced in August 2010 that he had been diagnosed with stage 4 throat cancer, the most advanced stage, after numerous specialists failed to identify the source of his oral discomfort. A doctor in Montreal finally discovered a walnut-sized tumor at the base of the actor's tongue.

On Aug. 31, 2010, Douglas spoke with David Letterman on the "Late Show" after completing his first week of radiation and chemotherapy. He was blunt about his diagnosis, but hopeful about his chances for recovery.

"Did they find it early enough for their liking," Letterman asked, regarding the actor's doctors. "I sure as s--- hope so," Douglas said to applause. He has now been cancer-free for two years.

Douglas can currently be seen in the HBO biopic "Behind the Candelabra," in which he stars as famed entertainer Liberace.