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In 2011, medical researchers reported that by inhibiting the PDE5 cellular pathway, melanoma cells could better invade and spread through the body. While investigators concluded that this could be a mechanism that contributes to melanoma’s virulence and aggressive behavior, there was another, potentially larger concern. PDE5 is the same pathway that drugs taken for erectile dysfunction (ED) inhibit to gain their effect. These drugs include Viagra (sildenafil), Cialis (Tadalafil), Lavitra (vardenafil) and Stendra (avanafil).
“When this report was released, investigators almost immediately asked the question: could Viagra cause melanoma?” says Dr. Adam Mamelak, board-certified dermatologist and skin cancer specialist in Austin Texas. Since then, there have since been two medical studies examining this question, with some interesting results.
The first study came out in 2014 with some shocking headlines: men that took Viagra were 84% more likely to develop melanoma skin cancer over 10 years compared to those who did not!
“Uproar was an understatement,” says Dr. Mamelak. “All of a sudden, men everywhere had a ‘new’ reason to be concerned about skin cancer.”
Dr. Mamelak however explains that these numbers have to be taken in perspective. The study actually followed close to 30,000 men who were enrolled in the Health Professionals’ Follow-up Study. Participants were given questionnaires every 2 years asking about their health and lifestyle. In the year 2000, questions about ED and treatments began to be included in these questionnaires.
“What they found was for every 1000 men not taking Viagra, there were 4.3 melanoma skin cancers. This compared to 8.6 melanomas for every 1000 men that took the drug.” According to the study, this was an 86% increase in skin cancers (after some statistical corrections).
While the numbers are impressive, Dr. Mamelak advises looking at these results in another way. “The study showed that there was an additional 4.3 cases of melanoma for every 1000 men that took the drug. That’s actually a 0.43% absolute increase in the number of melanoma cases.”
In 2015, a second Swedish study examining the relationship between ED drugs and melanoma was published. In this study, investigators looked at the portion of melanoma patients that had filled ED drug prescriptions, compared to non-melanoma patients that had similar prescriptions. Eleven percent of melanoma patients had filled ED prescriptions compared to 8% who had not. While the researchers suggested that there was a relationship between these medications and melanoma, it was not as clear cut.
“They actually stratified the cases of melanoma with the number of prescriptions the men received. The more prescriptions the men had, the the lower the association with melanoma,” explains Dr. Mamelak. “This means if men had multiple prescriptions, their initial increased risk of getting melanoma, appeared to decrease.”
These observations made investigators question whether ED drugs were truly associated with increase risk of skin cancer.
Whether the increased risk of melanoma with ED drugs is real or not, it pales in comparison to the risks associated with sunburns, UV exposure and unprotected sun. “More research is really needed to better define this relationship,” says Dr. Mamelak. “But that doesn’t mean that there aren’t other ways to protect your skin and optimize you skin’s health.” Excessive sun and UV exposure is still considered primary risk factor for developing skin damage and skin cancer.
Dr. Mamelak treats patients with melanoma and non-melanoma skin cancer including basal cell carcinoma and squamous cell carcinoma at Sanova Dermatology and The Austin Mohs Surgery Center.
If you are concerned about a skin lesion or want to learn more about skin cancer, please contact us today.