A study entitled “Sildenafil Use and Increased Risk of Incident Melanoma in US Men, A Prospective Cohort Study” and published in the JAMA Internal Medicine journal has shown that there may be a link between Viagra and melanoma skin cancer.
The RAS/RAF/mitogen-activated protein kinase and extracellular signal–regulated kinase (ERK) kinase/ERK cascade are key pathways for melanoma cell proliferation and survival.
Sildenafil citrate (Viagra) is a phosphodiesterase (PDE) 5A inhibitor commonly used for erectile dysfunction. Studies have shown that BRAF activation down-regulates PDE5A levels, and low PDE5A expression by BRAF activation or sildenafil use can increase the invasiveness of melanoma cells, raising the possible adverse effect of sildenafil use on melanoma risk.
To understand the link between sildenafil use and risk of incident melanoma among men in the United States, the research team designed a prospective cohort study and questioned participants in the Health Professionals’ Follow-up Study if they used sildenafil for erectile dysfunction.
Participants who already suffered from cancers at baseline were excluded, however, a total of 25,848 patients were analyzed in this study.
The incidence of skin cancers, including melanoma, squamous cell carcinoma (SCC), and basal cell carcinoma (BCC), was obtained in the self-reported questionnaires biennially, and the diagnosis of melanoma and SCC was pathologically confirmed.
The researchers found that men who used sildenafil were 84% more likely to develop melanoma over a period of 10 years.
The average age of men in the study was 65 and a total of 6% had taken Viagra to treat erectile dysfunction. The results demonstrated that, even after adjusting for family history of skin cancer, ultraviolet light exposure in the states where the men lived, other kinds of cancer and major illnesses, men who used Viagra had a doubled risk of developing melanoma when compared to those who never used the drug.
This effect was observed only for melanoma, since it was specific for low PDE5A expression. This meant that patients who took the drug weren’t at higher risk of other, less-dangerous skin cancers, such as basal cell or squamous cell cancers.
Whether a similar connection might exist between other erectile dysfunction drugs and melanoma isn’t known, since at the time the study was initiated, Viagra was the only erectile dysfunction drug on the market.
The authors state that even though this study is insufficient to alter clinical recommendations, there is a need for continued investigation of this particularly relevant association.
