Melanoma Risk with Viagra Seen in Study, But Causal Link Questioned

Amid continuing concerns that side effects of Viagra may increase the risk of skin cancer, new research seems to confirm an association between use of erectile dysfunction drugs and a diagnosis of melanoma. However, the researchers question whether Viagra or other similar medications may be the actual cause.

In a study published this week in the Journal of the American Medical Association (JAMA), researchers found that Viagra and other drugs that are part of a class of medications known as phosphodiesterase type 5 (PDE5 ) inhibitors were linked to a 32% increased risk of melanoma among white males.

Melanoma is a serious and potentially deadly form of skin cancer. Prior studies have identified a potential melanoma risk with Viagra, leading to a number of recent product liability lawsuits against Pfizer.

Despite the findings that users face an increased risk of being diagnosed with melanoma, researchers indicate that they found discrepancies in the numbers that suggest PDE5 inhibitors may not be the actual cause of these skin cancer cases. Instead, the increased risk may be a reflection of the lifestyle that men likely to use the drugs lead.

Researchers looked at Swedish medical records from 2006 to 2012 and found about 4,000 cases where men were diagnosed with melanoma skin cancer. About 11% of those men had filled a prescription for at least one PDE5 inhibitor.

According to the findings, men who filled just one prescription for the drugs were at 32% higher risk of melanoma than men who did not use the drugs. However, the number appeared to decline with use, with men who filled multiple prescriptions at only 14% higher risk.

Researchers determined that there were seven additional cases of melanoma per 100,000 men taking Viagra or a similar drugs.

“What our study results show is that groups of men who are more likely to get malignant melanoma include those with higher disposable incomes and education — men who likely can also afford more vacations in the sun — and who also have the means to buy erectile dysfunction medications, which are very expensive,” lead researcher, Dr. Stacy Loeb, a New York University Langone urologist, said in a university press release.

Viagra (sildenafil citrate) was introduced by Pfizer in 1998, and it has become a blockbuster medication and one of the most widely known prescription medications in the country.

The impotence drug has been aggressively promoted as a safe treatment for erectile dysfunction, which causes a number of men to experience sexual problems, including the inability to develop or maintain an erection.

Viagra and Melanoma

Concerns about the link between Viagra and melanoma surfaced early last year, when a study published by researchers from Harvard Medical School found that men who took Viagra were 84% more likely to be diagnosed with melanoma skin cancer than men who do not use the drug.

The Harvard study and other research prior to that have noted that there is a likely mechanism of action that can explain the increased melanoma risk with Viagra and other erectile dysfunction drugs. Researchers have noted that PDE5A is a cancer-fighting protein, and that the erectile dysfunction drugs lower both PDE5 and PDE5A. This could cause a reduction in the ability of the body to fight or contain cancer, allowing malignant melanoma cells to spread more rapidly.

As early as 2011, a study was published in the medical journal Cancer Cell which warned that Viagra could promote melanoma cell invasion. Another study published in the Journal of Cell Biochemistry in 2012 also found that PDE5 inhibitors like Viagra could exacerbate melanoma development.

The American Cancer Society indicates that melanoma is diagnosed in about 69,000 Americans each year and causes about 8,650 deaths annually. The skin cancer usually manifests as unusual moles or patches of skin. While it is often curable if caught early, once melanoma has spread beyond the skin and local lymph nodes, treatment is difficult and it may ultimately result in death.

Pfizer, the makers of Viagra, face a growing number of Viagra melanoma lawsuits by men who say they were diagnosed with melanoma after using the drug. The complaints allege that the drug maker aggressively marketed the erectile dysfunction drug without adequately researching the potential risk of melanoma or warning about the importance of monitoring for signs of skin cancer while taking the drug.