Risk of renal cancer in patients with inflammatory bowel disease: A pooled analysis of population-based studies

Background: Currently, newer epidemiological studies report the association between inflammatory bowel disease (IBD) and risk of renal cancer (RCa). Thus, we conducted a meta-analysis to determine whether IBD patients were associated with RCa risk. Methods: Various medical databases were searched from inception to April 2020. Standardized incidence ratio (SIR) or relative risk (RR) with corresponding 95% confidence intervals (CIs) were pooled. The meta-analysis was completed by STATA version 14.2. Results: A total of 421 articles were identified, and 11 studies met the inclusion criteria. Data from 9 cohort studies showed a significantly increased risk of RCa in IBD patients (pooled SIR: 1.53; 95%CI: 1.25–1.80; I2 = 42.4%), especially for patients with Crohn's disease (CD) (pooled SIR: 1.95; 95%CI: 1.45–2.44; I2 = 39.9%). We did not observe a significantly increased risk of RCa in patients with ulcerative colitis (UC) (pooled SIR: 1.31; 95%CI: 0.94–1.67; I2 = 48.0%) when compared to the background population. Only 2 case-control studies reported the results of RCa risk, showing no significant difference between IBD group and IBD-free group (pooled RR: 1.64; 95%CI: 0.52–5.22; I2 = 77.9%). Conclusions: Our findings indicate that IBD patients with special reference to CD patients have a significantly higher risk of RCa. Further studies are warranted to enable definite conclusions to be drawn.