A Canadian population-based cohort study revealed dose-dependent increases in skin cancer risk associated with thiazides in people aged 66 years and older. The study included a total of 302 634 adults aged ≥ 66 years prescribed an antihypertensive medication and 605 268 matched unexposed adults. Increasing thiazide exposure was associated with an increased rate of incident keratinocyte carcinoma (adjusted hazard ratios [HRs] per 1 Defined Annual Dose unit 1.08), advanced keratinocyte carcinoma (adjusted HR 1.07) and melanoma (adjusted HR 1.34). There was no consistent evidence of association between other anti-hypertensive classes and keratinocyte carcinoma or melanoma. The finding is consistent in direction with recent studies. Ultraviolet radiation exposure is the most important environmental risk factor for skin cancer. Antihypertensive medications such as thiazide diuretics have been reported to be phototoxic. Interventions that may decrease the risk including sun protection and monitoring for early detection of skin cancer, as well as alternatives to thiazide diuretics to treat hypertension in patients at high risk for skin cancer. Source: https://www.cmaj.ca/
