Michael Douglas -- Oral Sex Gave Me Cancer

Michael Douglas says his near-death bout with throat cancer was caused by an STD he picked up while giving oral sex. TMI, Michael!!!!

Douglas dropped the bombshell in an interview with the Guardian UK -- telling the paper that his particular form of throat cancer was caused by human papillomavirus (HPV) that was contracted from "cunnilingus" ... a.k.a performing oral sex on a female.

He explains, "It's a sexually transmitted disease that causes cancer. If you have it, cunnilingus is also the best cure for it." The last part is NOT supported by doctors.

FYI -- HPV is more famously known to cause cervical and anal cancer.

Douglas was diagnosed with stage 4 throat cancer back in 2010. He underwent weeks of radiation and chemo.