Photosensitizing agents and the risk of non-melanoma skin cancer: a population-based case-control study.

It is well-known that UV light exposure and a sun-sensitive phenotype are risk factors for the development of non-melanoma skin cancer (NMSC), including basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). In this New Hampshire population-based case-control study, we collected data from 5,072 individuals, including histologically confirmed cases of BCC and SCC, and controls via a personal interview to investigate possible associations between photosensitizing medication use and NMSC. After adjustment for potentially confounding factors (e.g., lifetime number of painful sunburns), we found a modest increase in risk of SCC (odds ratio (OR)=1.2, 95% confidence interval (CI)=1.0-1.4) and BCC (OR=1.2, 95% CI=0.9-1.5), in particular early-onset BCC, (≤ 50 years of age) (OR=1.5, 95% CI=1.1-2.1) associated with photosensitizing medication use. For SCC the association was strongest among those with tendency to sunburn rather than tan. We also specifically found associations with BCC, and especially early-onset BCC, and photosensitizing antimicrobials. In conclusion, certain commonly prescribed photosensitizing medications may enhance the risk of developing SCC, especially in individuals with a sun-sensitive phenotype, and may increase the risk of developing BCC and incidence of BCC at a younger age.