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.