Urological cancer risk in patients with rheumatoid arthritis compared to matched controls: a nationwide cohort study

Objective: Rheumatoid arthritis (RA) is a chronic inflammatory disease associated with several comorbidities, including an increased risk of certain cancers. This study aimed to investigate the potential associations between RA and increased risk of urological cancers – specifically kidney, bladder, prostate and testicular cancers – and the influence of RA serological status on this risk. Methods: This retrospective cohort study used data from the Korean National Health Insurance System database (2010–2020), including patients with RA and a 1:5 matched non-RA population. RA patients were grouped according to serological status. The primary outcome was newly diagnosed urological cancer, and its association with RA was analysed by Cox proportional hazards regression analyses adjusting for potential confounders. Results: RA patients had an increased risk of kidney cancer compared with the non-RA population fadjusted hazard ratio (aHR), 1.34 [95% confidence interval (CI), 1.04–1.78]g. The risk of kidney cancer was even higher in women with RA [aHR 1.57 (95% CI: 1.10, 2.24)]. However, the risk of bladder, prostate and testicular cancers was not associated with RA (bladder cancer, aHR 1.24, 95% CI 0.95–1.62; prostate cancer, aHR 1.13, 95% CI 0.94–1.35; testicular cancer, aHR 2.31, 95% CI 0.44–12.20). No significant difference in urological cancer risk was found according to serological status. Conclusions: RA patients have a higher risk of kidney cancer than the general population. Further research is needed to understand the mechanisms underlying the association between RA and kidney cancer to optimize cancer prevention and screening strategies.