Viagra Use Raises Skin Melanoma Risk

A new study cautions that men who used the erectile-function drug Viagra (sildenafil) had almost twice the risk of melanoma compared with men who never used the drug.

Researchers at Brigham and Women's Hospital, Harvard Medical School (Boston, MA, USA), Indiana University (Indianapolis, USA), and other institutions conducted a prospective cohort study that analyzed data from the Health Professionals Follow-up Study (HPFS), starting in 1986 with a total enrollment of 51,529 male health professionals aged 40 to 75. In the year 2000 follow-up, participants were questioned regarding sildenafil use for erectile dysfunction; those who reported cancers at baseline were excluded. A total of 25,848 men remained in the analysis.

During follow-up (through 2010), the researchers identified 142 melanoma, 580 squamous cell carcinoma (SCC), and 3,030 basal cell carcinoma (BCC) cases. Recent sildenafil use at baseline was significantly associated with an increased risk of subsequent melanoma. In contrast, no increased risk of SCC was associated. Moreover, erectile function itself was not associated with an altered risk of melanoma. The study was published in the June 2014 issue of JAMA Internal Medicine.

"Our study cannot prove cause and effect; a longer follow-up and more detailed assessment of the dose and frequency of sildenafil use at multiple times would be necessary for future studies,” concluded senior author Jiali Han, PhD, of the Indiana School of Public Health, and co-authors. “Nevertheless, our data provide epidemiological evidence on possible skin adverse effects of phosphodiesterase 5A inhibitors and support continued investigation of this relationship.”

Recent studies have shown that activation of the oncogenic BRAF gene (a member of the Raf kinase family of growth signal transduction protein kinases) down-regulates phosphodiesterase 5A (PDE5A) levels; a similar result occurs following sildenafil use. The low PDE5A expression increases the invasiveness of melanoma cells, which could explain the adverse effect of sildenafil on melanoma risk. If the association proves to be a real relationship, then the effect on melanoma risk probably applies to all drugs in the PDE5-inhibitor class.

Related Links:
Brigham and Women's Hospital, Harvard Medical School
Indiana University