Exploring the causal relationship between autoimmune diseases and gastrointestinal tumors: A two-sample Mendelian randomization study

Purpose: Autoimmune diseases (AID) may be associated with gastrointestinal cancer. This study used a two-sample Mendelian randomization method to examine the potential correlation between AID and gastrointestinal cancer. AD, such as sarcoidosis, Graves’ disease (GD), multiple sclerosis (MS), psoriasis, rheumatoid arthritis (RA), Sjögren’s syndrome (SS), systemic lupus erythematosus (SLE), type 1 diabetes (T1D), and celiac disease (CD), were selected. Gastrointestinal tumors include colorectal cancer (CRC), colonic pseudopolyposis, colorectal neuroendocrine tumors and carcinomas, and gastrointestinal stromal tumors and sarcomas. Methods: We used genome-wide association study data from the Finngen R10 database and the IEU study data. We employed the inverse variance-weighted method to explore the causal relationship between the exposure and outcomes. Results: Sarcoidosis and psoriasis were associated with a reduced risk of CRC, whereas GD was linked to an increased risk. SLE, RA, T1D, and GD are associated with a decreased risk of colonic pseudopolyps, whereas CD, sarcoidosis, psoriasis, and MS are associated with an increased risk.Sarcoidosis, SS, and T1D were associated with a reduced risk of colorectal neuroendocrine tumors and carcinomas, whereas CD and MS were associated with an increased risk. Sarcoidosis, SS, and MS are linked to a reduced risk of developing gastrointestinal stromal tumors and sarcomas, while RA is associated with an increased risk. Additionally, CRC is associated with an increased risk of sarcoidosis. Conclusion: Autoimmune diseases may be associated with the incidence and development of gastrointestinal tumors, whereas cancer may promote sarcoidosis.