London School of Hygiene & Tropical Medicine

A study published today in JAMA has shown that among men in Sweden, use of erectile dysfunctions drugs with phosphodiesterase type 5 inhibitors was associated with a modest but significant increased risk of malignant melanoma, although the pattern of association raises questions about whether this association is causal.

Commenting on this, Professor Stephen Evans, Professor of Pharmacoepidemiology at the London School of Hygiene & Tropical Medicine, said: 

"The authors of this study are appropriately cautious in the interpretation of their data. The estimate of increased risk is small, and reduced by adjusting for the available confounding factors. This adjustment will be incomplete inevitably because of imprecision in recording those factors. In addition a key factor is exposure to sun, and the data on this (and other possible relevant factors) were not available. The risk of malignant melanoma associated with increased income was notably larger than that associated with ED drugs. This may also be associated with exposure to sunlight. It may be the wealthy who are able to travel to the sun in Sweden's winter! It may be that those who travel are also more likely to use ED drugs.

"This study is extremely weak evidence for an increase in risk of malignant melanoma with ED drugs, and seems much more likely to be associated with other factors, especially exposure to sunlight."