This Study Rewards Promiscuity

Good news for straight men who like to play the field. A new study found that sleeping with more than 20 women lowers prostate cancer risks. Researchers at the University of Montreal and INRS-Institut Armand-Frappier interviewed 3,208 men on their sex lives and discovered that the ones who had more than 20 female sexual partners were less likely to be diagnosed with prostate cancer than men who had fewer partners.

Of the 3,208 male study participants, 1,590 were diagnosed with prostate cancer between September 2005 and August 2009. Based on these diagnoses and the men's answers in the questionnaire, the researchers concluded that men who have had sex with more than 20 women in their lifetime are 28 percent less likely to get prostate cancer of all types and 19 percent less likely to get the more aggressive types. The study, which was published in Cancer Epidemiology, also found that men who have never had sex were almost twice as likely to get prostate cancer — as if virgins didn't have it hard enough as it is.

Lead study author Marie-Elise Parent told the University of Montreal's news site UdeMNouvelles:

It is possible that having many female sexual partners results in a higher frequency of ejaculations, whose protective effect against prostate cancer has been previously observed in cohort studies.

This "protective effect" may be caused by the reduction of cancer-causing substances in prostatic fluid or a decrease in the production of intraluminal crystalloids, which are highly associated with prostate cancer.

So does this mean public health officials should start making PSAs encouraging men to get more aggressive on Tinder? ("Hey, if you don't want prostate cancer, you better get your weekend sorted out ... the more you know.") Slow your roll, Parent said, "we're not there yet."

On the other hand, the study also found that the opposite was true for gay men. While having only one male sexual partner did not affect the participants' risk of getting prostate cancer, having more than 20 male partners doubled their risk of being diagnosed with prostate cancer of all types. For the men who had slept with more than 20 male partners, their risk of developing a less-aggressive prostate cancer increased by 500 percent.

Parent offered her "highly speculative" hypothesis to UdeMNouvelles:

It could come from greater exposure to STIs, or it could be that anal intercourse produces physical trauma to the prostate.

Before a more official conclusion can be made, the researchers are happy to have a better understanding of how sexual activity is linked to prostate cancer in general. Parent offered her gratitude to the study participants for being so open.

We were fortunate to have participants from Montreal who were comfortable talking about their sexuality, no matter what sexual experiences they have had, and this openness would probably not have been the same 20 or 30 years ago. Indeed, thanks to them, we now know that the number and type of partners must be taken into account to better understand the causes of prostate cancer.

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