Could Viagra increase the risk of skin cancer

Could Viagra increase the risk of skin cancer It is prescribed to men battling the embarrassment of erectile dysfunction. But, while Viagra helps boost a man's performance in the bedroom, scientists have warned the drug could increase the risk of skin cancer. A new study has found men who rely on the medication to help their virility are at greater risk of melanoma - the deadliest form of skin cancer. Sildenafil, which is also sold under the brand name Revatio, has been on the market since the late 1990s. Scientists have long investigated possible links between the medication and cancer. A long-term study, published in 2014, of nearly 15,000 men in the US suggested that sildenafil increased the risk of malignant melanoma. The correlation was confirmed in 2015 in a study of nearly 24,000 men in Sweden. However, neither of the previous studies determined whether the increased melanoma risk stemmed from a biological effect of the drug on tumor cells. Nor could those studies discount the possibility that a higher incidence of skin cancer may be due to lifestyles, including sunbathing on holiday. The current study, however, found that sildenafil can encourage the growth of skin tumors. The drug has a stimulating effect on the messenger molecule cyclic guanosine monophosphate - or cGMP, researchers said. cGMP, in turn, promotes the growth of existing malignant melanomas. The scientists reached this conclusion through animal experiments and human cell cultures. Study author Professor Robert Feil said: 'We have discovered that the cells of malignant melanoma also use the cGMP signaling pathway for their growth.' Cells normally contain an enzyme - called phosphodiesterase type 5 (or PDE5) - that ensures the newly-formed cGMP is continuously broken down. However, sildenafil inhibits that enzyme. Professor Feil said: 'Taking sildenafil basically disables this brake.' As a result, the melanoma begins to grow more vigorously. Researchers said it is this biochemical mechanism that explains why men who take sildenafil have an increased risk of melanoma. However, the study noted that there is no reason for men to refrain from occasionally taking PDE5 inhibitors to treat erectile dysfunction. Professor Feil explained that further research is necessary to gauge the applicability of these findings on humans. He said: 'We are assuming that sildenafil and possibly other PDE5 inhibitors could first and foremost reinforce the growth of existing melanomas - particularly if these medications are taken frequently and in high dosages.' Findings from other studies indicate that sildenafil may actually inhibit other types of tumors - including certain intestinal tumors. However, melanoma patients are advised to consult with their doctors before taking the drugs. Professor Feil warned: 'Ultimately, we should all be thinking about reducing our risk of skin cancer and cutting our exposure time to the sun, as well as using effective UV protection.