If you do a search, you will see a lot of discussion that the initial appearance of an association between Viagra –class drugs and melanoma does not appear to be causual. It is easy to think of an example of how this could be true since elevated insulin and blood sugar are risks for both cancer and ED, but that does not mean that an ED drug causes the cancer even though they could be correlated. You will also see evidence of a possible protective affect for both some cancers and cardiovascular disease. So the net affect seems to most likely be positive and that is not counting the numerous quality of life benefits.