Health check: can sex affect your risk of getting cancer?

By Spring Chenoa Cooper, University of Sydney; Hayden Fletcher, University of Sydney, and Nial Wheate, University of Sydney

The sex act has many health benefits from reducing stress and tension, to boosting your immune system. It may even affect your risk of developing certain cancers.

But as with most matters health, how sex and cancer risk are linked is complicated and dependent on several factors. Your age, gender, and how often you practice safe sex will all influence your potential cancer risk.

To date, the only clear literature linking sex and cancer is that concerning the human papillomavirus (HPV). There are over 200 strains of HPV, but some are more cancer-causing than others. The good news is that we now have a vaccine against the most common cancer-causing strains of the virus.

Most commonly, HPV is linked to cervical cancer. But both men and women can increase their risk of developing cancer through sexual activities that pass on the virus.

HPV infection

A lot has been written about HPV and cervical cancer. So much, in fact, that most people don’t even realise men can also get HPV, and that they can get HPV-related cancers too. Indeed, men have largely been ignored in the media and promotion of the HPV vaccine.

Boys have been included in the Australian school-based HPV vaccination program since 2013. But preliminary results of research with male adolescents and their parents suggest there’s low awareness and understanding about the vaccine.

Adolescent boys aren’t sure what the vaccine is for, nor why they need to get it; parents think their sons are not at risk of HPV-related cancers. But HPV can cause a range of cancers in both men and women, in sites other than the cervix. These include cancers of the anus and genitals, as well as cancers of the head, neck, and throat.

Indeed, HPV infections are now a proportionally significant cause of oropharyngeal (head, neck, and throat) cancer diagnoses. And epidemiological modelling suggests that by 2020, HPV will cause more oropharyngeal cancers than cervical cancers in the United States.

In 2013, news reports of Hollywood veteran (and self-confessed ladies’ man) Michael Douglas identified HPV as the cause of his throat cancer, creating public interest in the relationship between sexual activity and cancer risk.

Unfortunately, some interpretations of this news were incorrect, leading people to believe that oral sex could also “cure” cancer after Douglas also made that claim. In fact, the only “cure” in the case of HPV-related cancers is prevention.

HPV vaccination

Vaccination is the primary method of preventing HPV-related cancers. But as mentioned above, some parents still question why males need the vaccine if girls are receiving it through the school-based program.

The reason is twofold.

Among heterosexual couples, HPV is transmitted between males and females (either partner could be infected first and transmit it to the other). So, vaccinating women provides some benefits to men, but full protection of heterosexual men only occurs if most women receive the vaccine.

While the school-based program in Australia has reached quite high coverage of girls, it isn’t high enough to fully protect all heterosexual boys. What’s more, men who are vaccinated will help protect future partners who are not vaccinated.

The second reason is that adolescent boys who do or will eventually identify as bisexual or homosexual are not protected. It’s unrealistic, impractical, and stigmatising to try to single out this population at the age of 12, when school children receive the HPV vaccine.

By vaccinating adolescent boys in a school-based program, we can protect the homosexual community from developing HPV-related cancers as well. And this is very important given the higher prevalence of HPV infection and related disease in this population.

HPV is a real risk for developing cancer in both men and women, and it is transmitted through sex. But, reducing this cancer risk is easily done through vaccination. After HPV vaccination, the only real cancer worries are those not directly related to sexual behaviours.

So get vaccinated against HPV, eat your veggies, exercise, and watch out for those other carcinogens in your life. But you won’t have to worry about contracting cancer from your sexual partners.

Nial Wheate in the past has received funding from the ACT Cancer Council, Tenovus Scotland, Medical Research Scotland, Scottish Crucible and the Scottish Universities Life Sciences Alliance for research into anticancer drugs.

Hayden Fletcher and Spring Chenoa Cooper do not work for, consult to, own shares in or receive funding from any company or organisation that would benefit from this article. They also have no relevant affiliations.

This article was originally published on The Conversation.
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