PDE5A and melanoma: A subsequent nationwide, population-based, nested case-control study in Sweden, including 4065 melanoma cases diagnosed from 2006 through 2012, showed that the use of PDE5 inhibitors was associated with a modest but statistically significant increased risk of malignant melanoma, but the pattern of association (e.g. the lack of association with multiple filled prescriptions) raises questions about the causality of this relationship [270].