Over recent years, there has been growing concern that Viagra and similar drugs increase the risk of melanoma.
A new large-scale meta-analysis concludes that this is not the case.
The erectile dysfunction drug, sildenafil – often sold as Viagra – is regularly used by millions of men. It is widely considered to be a relatively safe drug.
However, some studies have concluded that Viagra and other phosphodiesterase type 5 (PDE5) inhibitors increase the risk of melanoma – a deadly type of skin cancer.
Because of these findings, the Food and Drug Administration (FDA) added Viagra and similar medications to their watch list of drugs with potential health risks.
This action came after a study in the Journal of the American Medical Association (JAMA) was published in 2014.
The study involved data from more than 25,000 participants and linked an increased melanoma risk with Viagra usage.
Although the research seemed conclusive, others set out to replicate the results because of the importance of the findings.
Questioning the link
In 2015, Dr. Stacy Loeb, an urologist and assistant professor at NYU Langone Medical Center, analyzed data from more than 20,000 Swedish men.
This time, the conclusions were different.
The researchers found no evidence that Viagra and similar drugs cause an increase in melanoma risk.
Although there was a significant increased risk of melanoma in Viagra users, the authors concluded that “the pattern of association […] raises questions about whether this association is causal.”
In a follow-up study, published this week in the Journal of the National Cancer Institute, Loeb and her team took the analysis to the next level.
This time, they analyzed data from five large existing studies.
In all, data from 866,049 men was scrutinized. Of the subjects, 41,874 developed melanoma.
The researchers did find an 11 percent increased risk of melanoma in men taking PDE5 inhibitors, but the circumstances appears to be more complex and evidence for a causal link was lacking.
For instance, if there was a true link between the drug and melanoma, it should follow that men who take more of the Viagra-type medications are more likely to develop skin cancer.
What researchers actually found was that people taking more of the medication had no increased risk of melanoma. It was only men who were taking smaller amounts that experienced the increased risk.
The researchers also theorized that, if the medication was causing the melanoma, people taking the drug would have more aggressive forms of the disease than people who were not taking the drug. This was not the case.
Loeb did find an increased risk of early-stage melanoma among those taking PDE5 inhibitors, but they were at a lower risk for aggressive melanoma than non-users.
The authors write that the 11 percent increase in melanoma cases with erectile dysfunction medication was due to “detection bias.”
The conclusion is that people who take this type of medication are, on average, more health conscious and, therefore, more likely to see a doctor.
This behavior then increases detection rates of melanoma.
Loeb says: “Overall, Viagra and other PDE5 inhibitors are safe medications as long as men are not taking nitrates, which carry a risk of reducing blood pressure. Physicians and patients should not be concerned about taking these medications on account of worry about melanoma.”
Loeb said the findings might influence healthcare professionals in the future.
“Physicians should still screen for melanoma risk, but they do not need to add the use of Viagra and similar drugs to the list of screening criteria specifically,” she said. “In general, men should continue to be careful about the risk of any kind of skin cancer from excessive sun exposure and use sun protection.”
Although the current study utilized a vast quantity of data, the debate surrounding PDE5 inhibitors is likely to continue.
Because the drugs are used in such volume, it is important that any potential health concerns are thoroughly investigated.