The editor of Harvard Men’s Health Watch commented on new research that linked drugs like Viagra and Levitra to melanoma, and expressed some reservations.

A study published in the American Medical Association’s journal JAMA Internal Medicine found that men who took Viagra had an increased risk of developing melanoma. The study looked into the possibility due to laboratory research that indicated some chemicals in erectile dysfunction drugs like Viagra and Levitra may interfere with cancer-blocking chemicals in the body. Researchers discovered that Viagra patients had an increased risk of developing melanoma. The study used medical survey data from almost 30,000 men.

A recent article on Harvard Medical School’s Health Blog had some critiques of the way this article was handled in the media. Daniel Pendick, the chief editor of Harvard Men’s Health Watch, said that the study may have caused some undue panic thanks to sensational headlines. While the study found that patients taking Viagra had an increased risk of developing melanoma, the study was observational or epidemiological, as Pendick pointed out.

He noted that “epidemiological studies like this one tell you only who is at the scene of the crime, not who done it.” Epidemiological or observational studies rely on data collected from the environment rather than a controlled clinical trial where every variable is accounted for.

Another possible flaw in the data is that during the time of the study, Viagra was the only erectile dysfunction drug on the market. Since then, several new erectile dysfunction drugs like Levitra have entered the market. This means that the study has no data on Levitra, which has some similarities to Viagra.

However, in the JAMA Internal Medicine study, researchers did consider these limits. Within the constraints of an observational study, researchers tested for other factors that could influence the data. Via statistical analysis, a type of mathematics that allow researchers to evaluate the strength of connections in data, researchers tested for other possible connections in the data.

For example, researchers considered that erectile dysfunction itself could increase the risk of melanoma, and that the fact that many people with erectile dysfunction take drugs like Viagra could be confusing the data. However, researchers performed statistical analyses on individuals with erectile dysfunction who were not taking drugs like Viagra or Levitra and did not find an increased risk of developing melanoma.

Additionally, the study found that taking Viagra did not increase the risk of other types of skin cancer. Arguably, this specificity lends some credence to the link, as much as it can within the confines of an epidemiological research.

Pendick did point out that even if the relationship was causal, which cannot be “proven” per se in an epidemiologically study, the absolute risk is small. This means that for every 1,000 men taking Viagra, about 4.3 will get melanoma, if the link is really causal.

While this risk is relatively small, those 4.3 men who develop melanoma could face serious health consequences. A class action lawsuit investigation has been launched to explore the possibility of legal action against the makers of erectile dysfunction drugs like Viagra and Levitra, arguing that drug makers were aware — or reasonably should have been aware — of the risks associated with their drugs. Such a Viagra melanoma lawsuit could further allege that drug makers failed to adequately protect the public from these risks.