Sleeping With 20+ Women Cuts Guys' Cancer Risk Possibly because of frequent ejaculation By Matt Cantor, Newser User Posted Nov 2, 2014 11:34 AM CST 109 comments Comments Could sex with more women help prevent prostate cancer? (AP Photo/Damian Dovarganes, file) (Newser) – One defense against prostate cancer may be promiscuity. A study of men in Montreal finds that those who'd slept with more than 20 women had a 28% lower risk of prostate cancer than did men who'd had sex with just one woman, CBS News reports. As for virgins, they faced double the cancer risk faced by those who'd had sex, the Telegraph reports. The reasons behind the findings aren't clear, but lead researcher Marie-Elise Parent notes that frequent sex means more frequent ejaculation; earlier studies, she says, have indicated that frequent ejaculation helps prevent prostate cancer. But the findings, based on surveys of 3,200 subjects, didn't hold true for men sleeping with men, the Independent reports. Men who had sex exclusively with men and had had more than 20 partners actually saw twice the prostate cancer risk of men who'd never slept with men. Parent says she has only "highly speculative" explanations for that, and anyway, those findings weren't statistically significant. So is all this a good reason for men to run out and sleep with as many women as possible? Parent throws a little cold water on that particular fire: "I don't think we can say that. But I think men want to hear that," she says. What's more, recent research has also suggested prostate cancer could be tied to an STD.