Does Viagra Cause Melanoma?

You may have seen in the news recently stories like one published on June 4th, 2014 by CBS news entitled  Viagra may increase melanoma risk, study finds. Keep in mind; this is not a good article.

You may have seen in the news recently stories like one published on June 4th, 2014 by CBS news entitled Viagra may increase melanoma risk, study finds. Keep in mind; this is not a good article. This article starts off by stating, “The little blue pill used by men to boost bedroom performance may be detrimental in the great outdoors, according to new research. The study, published in JAMA Internal Medicine, found sildenafil, commonly known as Viagra, may increase a man’s risk for melanoma by as much as 84 percent.” In fact, you will not find that “84%” statistic anywhere in the original study (click here).

The original study describes some very technical biochemistry as the reason for suspecting that drugs like sildenafil (the active ingredient in Viagra) “…may be associated with an increased risk of developing melanoma.” This is different than causing melanoma. When the study was done, Levitra, Cialis, and Stendra were not yet on the market in the US. The theory is that drugs like Viagra, Levitra, and Cialis, which are called Phosphodiesterase 5A Inhibitors (PDE5i’s), can mimic an effect of a genetic mutation called BRAF that downregulates PDE5A levels. In plain terms, The study suggests that Viagra may in theory do the same thing that the gene for melanoma does, by the same mechanism.

But the statistics aren’t as clear as the CBS News and other articles may have us believe. The original study was an observational study that used surveys taken as part of the Health Professionals’ Follow-up Study (HPFS), an ongoing study where men submit answers to questionnaires every 2 years. This study looked at a period from 2000 to 2010 and correlated Viagra use with new diagnoses of melanoma.

The study also very clearly states that “Those using sildenafil were more likely to be older and obese, have family history of melanoma, and take physical examinations (they check their skin for suspicious moles), but were exposed to less sun light as adults (age 25-59 years).” What this means is that erectile dysfunction, and therefore use of drugs like Viagra, is more common in men who also have a family history of melanoma and are more likely to be less healthy overall. This makes sense when we interpret the study as a correlation between Viagra and melanoma, and not a cause and effect relationship. Correlation can also be described as coincidence. In other words, two things that tend to go together don’t necessarily cause each other. They could be different results of the same issue.

One article by the Harvard Health Blog eloquently states the flaws in the conventional interpretation by some other news outlets. It does an excellent job of properly interpreting the study, stating that the absolute increase from 4.3 cases of melanoma per 1000 patients not using Viagra to 8.6 cases of melanoma per 1000 patients who were using Viagra is only a 0.43% increase. Statistics are supposed to make data interpretation more meaningful, but in many cases, statistics can be used to manipulate data into suggesting different things. What the original study actually shows is that there were 70 cases of melanoma per 113,515 person years in the group that had never used Viagra and 9 cases of melanoma per 5774 person years in the group that had used Viagra. A person year takes into account that the study analyzed data over a 10 year time period. This comes out to 0.6 cases per 1000 person hours for non-users vs. 1.6 cases of melanoma per 1000 person hours in the Viagra group. This is an increase of just one tenth of a percent. Even if it is statistically significant, in the real world it is far too soon to make such a claim, especially considering that users of Viagra type medications are more likely to have a family history of melanoma and be less healthy overall than non-users.

Should you worry about melanoma if you’re taking medications for erectile dysfunction? Everyone should be cautions when it comes to melanoma. If you have a family history, it doesn’t matter if you are taking Viagra or not. The only conclusions that can be taken from this study are that more research needs to be done to establish a true connection. At this point, all that can be said is that melanoma was seen slightly more often in users of Viagra than in non-users. The relationship could be pure coincidence, and the study also showed absolutely no connection at all between Viagra use and any other type of cancer. We suggest all people, especially those with a family history of skin cancer, protect themselves from excess sun exposure and do routine self-checks and doctor checks to identify suspicious moles that could be cancerous.