Personal history of psoriasis and risk of nonmelanoma skin cancer (NMSC) among women in the United States: A population-based cohort study

Abstract

Toour knowledge, no prospective studies have examined the association between personal history of psoriasis and risk of nonmelanoma skin cancer. We sought to examine this association based on 2 prospective cohorts, the Nurses' Health Study and Nurses' Health Study II. Diagnoses of nonmelanoma skin cancer, including basal cell carcinoma and squamous cell carcinoma (SCC), were obtained by self-reported questionnaires. Information on clinician-diagnosed psoriasis and diagnosis year was collected and validated with a supplementary questionnaire. After 2,487,941 and 2,478,148 person-years of follow-up, we documented 1725 SCC cases and 16,075 basal cell carcinoma cases, respectively. For the combined cohorts, personal history of psoriasis was associated with an elevated risk of SCC, with a multivariate-adjusted relative risk (RR) of 1.51 (95% confidence interval [CI] 1.11-2.05). The associations appeared stronger with increasing psoriasis severity, with RR of 1.42 (95% CI 0.94-2.15) in the mild psoriasis group and RR of 1.99 (95% CI 0.74-5.32) in the moderate to severe psoriasis group (P trend=.03). There was no association between psoriasis and the risk of basal cell carcinoma (RR 0.95; 95% CI 0.75-1.18). Lack of treatment data may bias the result. Personal history of psoriasis may be associated with an increased risk of SCC. Further investigations are warranted to understand the underlying mechanisms.