Association between autoimmune disease and colorectal cancer: a retrospective case-control study of 120 876 patients.

Objective: Colorectal cancer (CRC) is one of the most frequently diagnosed cancers and a leading cause of cancer-related deaths worldwide. While inflammatory bowel disease (IBD) is a well-established risk factor for CRC, the potential link between other autoimmune diseases and CRC is unclear. In light of the growing prevalence of autoimmune diseases and their recognised link to various malignancies, this study seeks to investigate whether different autoimmune diseases are associated with CRC.

Methods: A total of 20 146 patients with an initial diagnosis of CRC and 100 730 propensity score-matched cancer-free individuals were identified from the Disease Analyzer database (IQVIA). Univariable conditional logistic regression models were used to examine whether each autoimmune disorder was associated with subsequent CRC diagnosis.

Results: Only IBD was significantly associated with CRC (OR 1.53; 95% CI 1.33 to 1.75). Type 1 diabetes, rheumatic diseases, autoimmune thyroiditis, and multiple sclerosis did not show a significant association with CRC. Psoriasis showed a non-significant trend towards an association with CRC (OR 1.11; 95% CI 0.97 to 1.27). Coeliac disease was not associated with the development of CRC (OR 1.06; 95% CI 0.69 to 1.64). A sex-stratified analysis revealed that the association between IBD and CRC was similar in both women (OR 1.48; 95% CI 1.22 to 1.81) and men (OR 1.57; 95% CI 1.29 to 1.89). No significant sex differences for any other autoimmune disease were observed.

Conclusion: The presence of IBD, but not any other autoimmune diseases, was significantly associated with a subsequent CRC. This finding serves to emphasise the significance of routine screening for patients suffering from IBD.