When the drug sildenafil (Viagra) was approved for the treatment of erectile dysfunction (ED) in 1998, the “little blue pill” quickly became the punch line of many a joke on late-night television. It also became big business, with billions of dollars in sales per year.

Melanoma, the deadly form of skin cancer, has big numbers, too. It’s the eighth most common cancer diagnosis…and it kills nearly 10,000 people in the US each year.

What do Viagra and similar drugs have to do with melanoma, you may wonder? Perhaps quite a lot, according to the latest research—and I assure you, it’s no joke. Here’s what men need to know to protect themselves…

GOOD FOR SEX, BAD FOR SKIN

Researchers used data from the Health Professionals’ Follow-up Study that began back in 1986 when nearly 52,000 male health professionals completed a questionnaire on their medical history and lifestyle practices. The men were between 40 and 75 years old at the beginning of the study. Then, every two years thereafter, participants updated their info using additional questionnaires.

In 2000, cancer-free participants were asked whether they had ever been treated for erectile problems and whether they had used sildenafil. (Other ED drugs that work in similar ways were not approved until 2003, so they weren’t included in this analysis.) The study also gathered data on the men’s known skin cancer risk factors—number of moles, natural hair color, history of blistering sunburns, places of residence (to assess ultraviolet light exposure), family history of melanoma, etc. Of the nearly 26,000 men who completed this questionnaire, 5.3% reported taking sildenafil for ED in the previous few months and 6.3% reported having used it at any time.

Then, tracking the men until 2010, the researchers found that 142 participants developed melanoma and 3,610 developed nonmelanoma skin cancer. After adjusting for the effects of various known melanoma risk factors, the researchers discovered that…

  • Use of sildenafil at any time was associated with 92% increased risk for melanoma, while recent use was associated with an 84% increased risk, compared with men who did not use the drug at all.
  • There was no difference in risk for nonmelanoma skin cancers (such as squamous cell and basal cell skin cancer) between the men who had used the ED drug and those who had not. Given that certain factors such as sun exposure affect a person’s risk for all three main types of skin cancer, the lack of any link between the nonmelanoma skin cancers and ED medication suggests that the drug has some detrimental effect with regard to melanoma specifically.
  • When participants who had diabetes, high blood pressure or heart disease were excluded (since these conditions can affect sexual function), the association between sildenafil use and melanoma was even more pronounced. Compared with men who never used the ED drug, recent users had a 2.24 times higher risk for melanoma, while those who had ever used it had a 2.77 times higher risk.
  • No association was found between ED itself and increased melanoma risk…meaning that the drug, rather than the condition the drug was meant to treat, appeared to be responsible for the link.

WHAT’S THE CONNECTION?

Sildenafil and the other ED drugs approved later on—tadalafil (Cialis) and vardenafil (Levitra)—work by inhibiting an enzyme called PDE5A. That then leads to other changes that allow smooth muscle relaxation, improved blood flow and, voilà, penile erection. That same enzyme, however, also would normally work against melanoma cell proliferation, especially in the 50% of melanoma tumors that are fueled by a particular genetic mutation. In other words, by taking ED drugs that target PDE5A, men may be opening a chemical pathway that allows melanoma cells to flourish.

This study does not prove that ED drugs cause melanoma…and it was not designed to address questions about medication dosages, cumulative effects of long-term use or the relative risks of the various types of ED drugs. But clearly, men should now be on alert about this risk, and more research is needed—especially considering the fact that melanoma rates are increasing most rapidly in men over age 50…the same group that is most likely to use ED medication.

If you have taken or are considering taking any ED medication: Talk to your doctor about how to weigh the benefits against the potential dangers, including an increased risk for melanoma…discuss the lifestyle changes and alternative treatments that can improve sexual function without drugs…and be especially sure to get regular whole-body skin checkups from your dermatologist.