A meta-analysis by Tang et al. [71] concluded that PDE5 inhibitor use was associated with a slightly elevated risk of melanoma (OR, 1.12; 95% CI 1.03–1.21) and basal cell carcinoma (OR, 1.14; 95% CI 1.09–1.19) but not squamous cell carcinoma, however they concluded that causality remained elusive. The gene discussed is PDE5A; the disease is melanoma.