Risk of uncommon cancers in patients with psoriasis: a Danish nationwide cohort study

Background Cancer-associated mortality is increased in psoriasis. However, little is known about the risk of less common cancers. Objective We aimed to evaluate the risk of less common cancers in patients with psoriasis compared to persons without psoriasis using a nationwide cohort study. Methods Between 1 January 2008 and 31 December 2012, we identified all Danish patients with a first-time hospital diagnosis of a less common cancer defined as <100 new cases/year/100.000 persons in Denmark. The primary endpoint was the occurrence of a diagnosis of cancer. Results We included 4 361 869 individuals. Of these, 58 138 were classified as having psoriasis. After adjusting for age, sex, socio-economic status and healthcare consumption, we found significantly elevated hazard ratios for cancers of bone and cartilage (HR 4.97 [2.32-10.62], P < 0.0001) in patients with psoriasis on systemic treatment. Conclusion We provide further evidence of an increased cancer of bone and cartilage risk in patients with psoriasis.