Do Thiazide Diuretics Increase the Risk of Skin Cancer? A Critical Review of the Scientific Evidence and Updated Meta-Analysis.

We reviewed the hypothesised mechanisms of skin cancerogenesis for thiazide diuretics; conducted an updated meta-analysis of studies focusing on their association with skin cancer risk; critically appraised the quality of available studies and identified knowledge gaps; and discussed implications for health professionals and patients. Thiazide diuretics possess well-described photosensitizing properties and a causal association with skin cancer is biologically plausible. The epidemiological evidence is stronger for squamous cell cancer; however, diversity in design among studies, methodological concerns potentially affecting the validity of results, and scarcity of data on dose-relation relationship suggest caution in drawing conclusions. Only few, unbalanced, and/or heterogeneous data exist to date for melanoma and basal cell cancer. Patients effectively treated with thiazide diuretics are currently not advised to stop treatment, but encouraged to limit exposure to sunlight and regularly check their skin. While endorsing these recommendations, we believe that well-designed studies are urgently needed to overcome persistent knowledge gaps.