Malignancy incidence in patients with psoriatic arthritis: a comparison cohort-based incidence study.

Malignancy is a major cause of death in patients with inflammatory disease. The risk of individual malignancies is altered in some inflammatory diseases, such as rheumatoid arthritis and psoriasis. This study aimed to examine malignancy incidence in patients with psoriatic arthritis (PsA), a related inflammatory disease. Institutional cancer registry and medical record linkage systems were retrospectively reviewed in a population-based incidence cohort of 217 patients with PsA and 434 age- and sex-matched comparators. Malignancy rates were compared using adjusted Cox models. Incidence of overall malignancy (excluding NMSC; hazard ratio (HR) 1.64; 95 % confidence interval (CI) 1.03-2.61) and breast cancer (HR 3.59; 95 % CI 1.22-10.61), but not NMSC (HR 1.23; 95 % CI 0.72-2.09), were significantly elevated in the PsA cohort. Age and female sex were similar predisposing risk factors in both cohorts. The overall incidence of malignancy, as well as the risk of breast cancer, was higher in patients with PsA than in the general population.