A recent evaluation of data of Swedish Men who used erectile dysfunction (ED) medications such as sildenafil (Viagra, Pfizer Inc), vardenafil (Levitra, Bayer HealthCare Pharmaceuticals), and tadalafil (Cialis, Eli Lilly and Company) found a significantly increased risk of developing melanoma and basal cell carcinoma, the most common form of skin cancer, compared to an aged-matched control group. Married men and those with higher educational levels and incomes were also at significantly increased risk for melanoma. Interestingly, the risk was highest among men who filled only a single prescription for one of the medications. If a causal relationship between the medications and melanoma existed, men who filled the most prescriptions would be expected to have the highest risk. It’s most likely that the same types of men who are at risk for melanoma (i.e. a lifestyle with increased sun exposure) also happen to take ED medications.
Another large study that looked at the dietary patterns of more than 100,000 Americans discovered that those who consumed citrus—specifically whole grapefruit or orange juice—daily had a 36% higher risk of developing melanoma. It is theorized that the increased risk might be due to the presence of furocoumarins in citrus which are known to make the skin more sensitive to sunlight. The American Society of Clinical Oncology called the findings “intriguing” but said that it’s too early to make any changes to dietary recommendations. The results have also been criticized due to various issues with the study design.
The best ways to prevent the development of skin cancer are sun avoidance and sun protection measures including the use of broad-spectrum sunscreens with a minimal SPF of 30, hats, and protective clothing.
Referrences: JAMA. 2015;313(24):2449-2455. doi:10.1001/jama.2015.6604. Citrus Consumption and Risk of Cutaneous Malignant Melanoma JCO published online on June 29, 2015; DOI:10.1200/JCO.2014.57.4111.