PDE5 inhibitors for erectile dysfunction unlikely to increase risk of skin cancer

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The PLOS Medicine Journal has published the findings of Researchers from the London School of Hygiene & Tropical Medicine which found that men who took sildenafil, tadalafil, and vardenafil had only a very slight increase in risk of malignant melanoma compared to a control group, which appeared to be explained by greater exposure to the sun.

According to the study, the three drugs are known to inhibit the enzyme phosphodiesterase type 5 (PDE5), and reduced expression of this enzyme has been linked to increased growth of melanoma cells in vitro. Epidemiological studies are therefore important to examine the possibility of a long-term increase in melanoma risk in men taking these PDE5 inhibitors for erectile dysfunction. It is interesting to note that previous studies on a possible increase in melanoma risk in men have come to conflicting conclusions, and this is why Anthony Matthews and colleagues embarked on a large study in United Kingdom men, using anonymized data from the Clinical Research Practice Datalink.

The study involved a comparison of 145,104 men prescribed a PDE5 inhibitor with 560,933 controls. The researchers observed an insignificant increase in risk of cutaneous melanoma (adjusted hazard ratio 1.14, 95% CI 1.01-1.29, p=0.04). However, similar increases in risk of basal cell carcinoma and solar keratosis, which are known to be related to sun exposure, were observed, while there was no increase in risk of colorectal carcinoma, which is unrelated to sun exposure. In addition, the group of men prescribed a PDE5 inhibitor experienced a higher risk of solar keratosis even in the period before receiving their first prescription, suggesting that they had higher rates of sun exposure on average than the control group. Krishnan Bhaskaran, the study’s senior author, said that their observations pointed towards the small apparent increase in risk of melanoma in men prescribed PDE5 inhibitors being explained by greater sun exposure, rather than a side-effect of the drugs themselves. The study further reveals the value of large-scale studies using clinical information gathered in primary care.

Article: Phosphodiesterase Type 5 Inhibitors and Risk of Malignant Melanoma: Matched Cohort Study Using Primary Care Data from the UK Clinical Practice Research Datalink, Matthews A, Langan SM, Douglas IJ , Smeeth L, Bhaskaran K,PLoS Medicine, doi:10.1371/journal.pmed.1002037, published 14 June 2016. Source: PLOS Medicine