A study of men taking PDE5 inhibitors found a small but significant increase in the incidence of malignant melanoma, though the association may not be causal.
In a Swedish study of men taking phosphodiesterase type 5 (PDE5) inhibitors, researchers saw a small but significant increase in the incidence of malignant melanoma. But, this does not prove that the association is causal, according to study authors. The results of the study were published in JAMA.
“What our study results show is that groups of men who are more likely to get malignant melanoma include those with higher disposable incomes and education-men who likely can also afford more vacations in the sun-and who also have the means to buy erectile dysfunction medications,” said lead study author Stacy Loeb, MD, MSc, of the department of urology at NYU Langone Medical Center in New York, in a statement.
Loeb and coauthors analyzed the medical records of men included in the Swedish Prescribed Drug Register, among others, who used sildenafil, tadalafil, or vardenafil. A total of 4,065 cases of melanoma were diagnosed. Of these, 435 (11%) had filled a prescription for a PDE5 inhibitor. Eight percent of the 20,325 men in the control group with no melanoma diagnosis filled at least one of these prescriptions.
Men who took a PDE5 inhibitor had a 21% increased risk of being diagnosed with melanoma compared with those who did not take these drugs. The risk of a melanoma diagnosis was highest among those who filled a single PDE5 inhibitor prescription-an increase of 32%. The risk among men who filled multiple prescriptions was between 14% and 17%, depending on the number of prescriptions filled. The increased risks with PDE5 inhibitors were associated with stage 0 or 1 melanoma. Risk was similar for all three drugs.
Because the results did not show a higher risk with greater drug exposure, the authors believe that the link may not be direct but rather due to other factors including lifestyle. Additionally, higher education level and higher annual income were also associated with an increased risk of melanoma.
The study researchers also saw a 19% increased risk for basal cell carcinoma (BCC) with the use of PDE5 inhibitors. Originally, the concern that PDE5 inhibitors may contribute to melanoma risk was partly due to the observation that the PDE5 enzyme is part of the MAP kinase pathway, which is upregulated in melanoma. But, this pathway has not been shown to be important in BCC.
“When used appropriately, erectile dysfunction medications are very effective and improve the quality of life for many men, so men should know it is doubtful that taking these medications puts them at greater risk of getting skin cancer,” concluded Loeb.