A Photosensitizing Drug and Risk for Skin Cancer
Cutaneous squamous cell carcinoma (cSCC) and basal cell carcinoma (BCC)—collectively termed nonmelanoma skin cancers (NMSC)—are the most common human malignancies, with a growing incidence both in the United States and worldwide.[1,2] In the United States alone, more than 700,000 new cases of cSCC are reported each year, and over 3000 deaths annually are attributable to it.[2]
Established risk factors for NMSC include a light skin phototype, immunosuppression, family history of NMSC, and heavy ultraviolet light exposure through natural or artificial sources.[3]
The antihypertensive drug hydrochlorothiazide (HCTZ) is a potent photosensitizer, associated with phototoxic and photoallergic skin reactions as well as drug-induced lupus.[4] HCTZ has also been shown to enhance UVA-induced DNA damage in an experimental model[5] and to increase the incidence of SCC of the lip up to sevenfold in a recent Danish case-control study.[6]
Because HCTZ remains one of the most commonly prescribed diuretics in the United States and Western Europe, Pedersen and colleagues[7]sought to explore any link between chronic thiazide use and NMSC. To accomplish this, they designed a case-control study using the Danish Cancer Registry (2004-2012) to gather 71,533 cases of BCC and 8629 cases of SCC. They cross-referenced these cases with the National Prescription Registry to determine cumulative HCTZ exposure, comparing these data with those of population controls.
