Photosensitizing antihypertensive drug use and risk of cutaneous squamous cell carcinoma

Background Many antihypertensive drugs (ADs) are photosensitizing, heightening reactivity of the skin to sunlight. Photosensitizing ADs have been associated with lip cancer, but whether they impact the risk of cutaneous squamous cell carcinoma (cSCC) is unknown. Objectives Methods To examine the association between AD use and cSCC risk among a cohort of non-Hispanic white individuals with hypertension enrolled in a comprehensive integrated healthcare delivery system in northern California (n = 28 357). Electronic pharmacy data were used to determine exposure to ADs, which were classified as photosensitizing, nonphotosensitizing or unknown, based on published literature. We identified patients who developed a cSCC during follow-up (n = 3010). We used Cox modelling to estimate adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs). Covariates included age, sex, smoking, comorbidities, history of cSCC and actinic keratosis, survey year, healthcare utilization, length of health plan membership and history of photosensitizing AD use. Results Conclusions Compared with nonuse of ADs, risk of cSCC was increased with ever having used photosensitizing ADs (aHR = 1 center dot 17, 95% CI 1 center dot 07-1 center dot 28) and ever having used ADs of unknown photosensitizing potential (aHR = 1 center dot 11, 95% CI 1 center dot 02-1 center dot 20), whereas no association was seen with ever having used nonphotosensitizing ADs (aHR = 0 center dot 99; 95% CI 0 center dot 91-1 center dot 07). Additionally, there was a modest increased risk with an increased number of prescriptions for photosensitizing ADs (aHR = 1 center dot 12, 95% CI 1 center dot 02-1 center dot 24; aHR = 1 center dot 19, 95% CI 1 center dot 06-1 center dot 34; aHR = 1 center dot 41, 95% CI 1 center dot 20-1 center dot 67 for one to seven, eight to 15 and >= 16 fills, respectively). These findings provide moderate support for an increased cSCC risk among individuals treated with photosensitizing ADs.