Reduced frequency of non-melanoma skin cancer in 72,739 patients with psoriasis: A retrospective study

Background: Chronic inflammatory conditions, such as psoriasis, may pose an increased risk of cancer due to impaired immunosurveillance resulting from chronic inflammation and immunosuppressive medications. Objectives: To compare the risk of non-melanoma skin cancer (NMSC) in a retrospective cohort of 72,739 psoriasis patients and 25,956 non-dermatological patients. Materials & methods: A record linkage was performed for data on hospitalizations, and the occurrence of NMSC was compared by computing the relative risk (RR) and modelled using multiple logistic regression. Results: Overall, the occurrence of NMSC was 9.6‰ (95% CI: 8.9-10.3‰) in psoriasis patients and 19.6‰ (95% CI: 18.0-21.4‰) in non-dermatological patients (RR = 0.49; 95% CI: 0.44-0.55). The simultaneous adjustment for gender, age, and phototherapy yielded a RR of 0.84 (95% CI: 0.75-0.95). With regards to phototherapy, the occurrence of NMSC was significantly higher among psoriasis patients who underwent phototherapy relative to those who did not (27.0‰ vs. 9.3‰). Conclusions: In this large retrospective study, we found that patients with psoriasis had a 16% lower probability of having NMSC when compared to a group of non-dermatological patients. Further studies, preferably with a prospective longitudinal design to collect more precise data, are needed to corroborate our findings.