High-ceiling diuretics are associated with an increased risk of basal cell carcinoma in a population-based follow-up study

Introduction: In Caucasians, basal cell carcinoma (BCC) is among the most frequently diagnosed cancers and its incidence is increasing. Known risk factors for the development of BCC are age, sun exposure, and certain skin characteristics. Despite photosensitizing abilities of diuretic agents, little is known about a possible association with BCC. Methods: Data were obtained from the Rotterdam Study; a large prospective populationbased follow-up study with coverage of prescription-only drugs from pharmacies. The diagnoses of BCC were obtained through general practitioners, and by linkage with a registry of histo- and cytopathology. Cumulative use of diuretics at the date of diagnosis was categorized into quartiles for users of high-ceiling diuretics, potassium sparing agents and thiazides. The association between these drugs and BCC was assessed by Cox proportional hazard modeling with adjustment for age, gender and potential confounders. Effect modification was tested with interaction terms. Results: Use of high-ceiling diuretics in the highest quartile (>3.7 years cumulative exposure) was associated with an increased hazard of BCC of 62% compared to no use (HR 1.6; 95% CI 1.1-2.4). Patients who used high-ceiling diuretics and had a high tendency of getting sunburned had a higher risk of diagnosis than non-users who do not easily get sunburned. Neither the use of potassium sparing agents, nor the use of thiazides was associated with BCC. Conclusion: In our study, cumulative use of high-ceiling diuretics was associated with an increased risk of diagnosis of BCC. This effect is stronger in patients who easily get sunburned. (C) 2010 Published by Elsevier Ltd