Autoimmune diseases and risk of gastrointestinal cancer: an umbrella review of meta-analyses of observational studies.

Abstract

Background: Several autoimmune diseases (ADs) are considered risk factors for gastrointestinal (GI) cancers. This study pooled and appraised the evidence associating ADs with GI cancer risks.

Methods: Three databases were examined from initiation through 26 January 2024. Evidence was determined by the criteria including the P -value of random-effects, small-study effects, excess significance bias, heterogeneity, and 95% prediction interval.

Results: Fourteen meta-analyses including 211 primary studies describing 31 associations were selected. Inflammatory bowel disease (IBD) and Crohn's disease (CD) are strong risk factors (with effect sizes of 10.33 and 12.12, respectively) for small bowel cancer (SBC), as indicated by highly suggestive evidence. Another highly suggestive evidence is that gastric cancer (GC) risk was elevated in individuals suffering from pernicious anemia (PA, effect size: 2.80). Suggestive evidence emerged that the risks of colorectal cancer (CRC) were decreased in patients with rheumatoid arthritis (RA, effect size: 0.79) but increased in patients with IBD (effect size: 1.82).

Conclusions: This study finds three highly suggestive pieces of evidence of IBD and CD patients with higher SBC risk and PA patients with higher GC risk. Future studies should identify these associations to provide more personalized cancer screenings for patients with ADs.