Risk of cancer in Korean patients with psoriatic arthritis: a nationwide population-based cohort study

OBJECTIVE: While many studies on the increased risk of cancer in patients with psoriasis are available, data on the risk of cancer in patients with psoriatic arthritis (PsA) are still scarce. We assessed the risk of cancer in patients with PsA in a nationwide population-based cohort in Korea. METHODS: From 2010 to June 2021, patients newly diagnosed with PsA and 1:10 age-matched and sex-matched controls were included in this study. The outcome was the incidence of overall and specific cancers. RESULTS: Total 162 cancers occurred in 4688 PsA patients (incidence rate 83.2 (95% CI 70.8 to 97.0) per 10 000 person-years) and 1307 cancers occurred in 46 880 controls (incidence rate 66.9 (95% CI 63.3 to 70.6) per 10 000 person-years). The adjusted HR (aHR) of overall cancer in PsA patients was 1.20 (95% CI 1.02 to 1.41). However, this significance disappeared when non-melanoma skin cancer (NMSC) was excluded (aHR 1.16, 95% CI 0.98 to 1.37). Among specific cancers, the risk of NMSC (aHR 3.64 (95% CI 1.61 to 8.23)), lymphoma (aHR 2.63 (95% CI 1.30 to 5.30)) and thyroid cancer (aHR 1.83 (95% CI 1.18 to 2.85)) was higher in patients with PsA than in controls. CONCLUSION: The risk of overall cancer was higher in patients with PsA than in the general population. Patients with PsA had increased risks of NMSC, lymphoma and thyroid cancer compared with the general population. Our findings suggest a need to conduct cancer screening by a detailed history and comprehensive clinical examination in patients with PsA.