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 parts per thousand (95% CI: 8.9-10.3 parts per thousand) in psoriasis patients and 19.6 parts per thousand (95% CI: 18.0-21.4 parts per thousand) 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 parts per thousand vs. 9.3 parts per thousand). 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.