How the number of sex partners you've had might affect your cancer odds, explained.

By Karen Asp
Updated March 10, 2020
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It’s 2020, and the stigma around how many people you've hooked up with is just not something to be concerned with. After all, there’s absolutely nothing wrong with playing the field...or not playing it, if that's your choice. But even though there is no right or wrong number, your “body count,” or the number of people you’ve had sex with, may play a role in your risk of developing cancer. 

 In a recent study published in BMJ Sexual and Reproductive Health, researchers evaluated data from the English Longitudinal Study of Ageing, which tracks individuals ages 50 and up who live in England. Subjects included 2,537 men and 3,185 women—their average age was 64 and almost three in four were married—who answered questions about how many sexual partners they’d had. Categories were broken into the following:  0-1, 2-4, 5-9, and 10 or more. 

Turns out, as the number of sexual partners increased, so did the percentage of individuals diagnosed with cancer. Women who reported having 10 or more partners were 91% more likely to have been diagnosed with cancer versus women who had none or one partner. Meanwhile, men who claimed to have had at least 10 sexual partners were 69% more likely to have been diagnosed with cancer versus men who’d had zero to one.

“We expected there to be an association between number of sexual partners and cancer risk, as previous research has shown that specific sexually transmitted infections (STIs) may lead to several cancers, and indeed, a higher number of sexual partners means greater exposure to STIs” says Lee Smith, PhD, study co-author and reader in physical activity and public health at Anglia Ruskin University in the United Kingdom. 

Why the difference between men and women? “It may be that the link between certain STIs and cancer is stronger in women, such as HPV (human papillomavirus) and cervical cancer compared to HPV and penile cancer,” Smith says. Refresher: Certain strains of HPV, an STI transmitted via skin to skin contact, can cause cell changes in the cervix that may lead to cervical cancer.

 Of course, nobody’s saying you shouldn’t have sex. After all, it’s good for you, says Smith, and leads to a reduced risk of cardiovascular disease, better self-rated health, higher quality of life, greater enjoyment of life, and overall better well being. 

And no one is making the case that having a lot of sex partners causes cancer; the study only discovered a link between people with higher body counts and cases of cancer. Also, take into account what a 91% higher risk of cancer actually means. Compared to those who slept with zero to one people, people whose body count numbered 10 or more were twice as likely to have been diagnosed with cancer. It doesn't mean that 91% developed cancer.

Worried if your number of partners is high? This might relax you: The study subjects who developed cancer "were also more likely to drink and smoke, which is also associated with a higher risk of cancer, so it could be a clustering of these unhealthy behaviors that’s driving the risk up,” says Smith.

But since the higher cancer risk could be related to STIs, it's wise to lower your risk of contracting one of these by using condoms (not 100% foolproof, but still better than nada), and then get tested regularly so if you do have an STI, you can treat or manage it sooner rather than later. Also, don't skip the HPV vaccine. Newer versions of the vaccine are up to 90% effective at protecting you from cancer-causing strains of HPV, according to Mary Jane Minkin, MD, clinical professor of ob-gyn at Yale University.

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