No genetic causality between appendectomy and gastrointestinal cancers: a Mendelian randomization study and meta-analysis in European population

The impact of appendectomy on the risk of gastrointestinal cancers remains unknown. We aimed to systematically estimate the causal relationship between appendectomy and gastrointestinal cancers in the European population using two-sample Mendelian randomization (TSMR) study methods and meta-analysis. As part of the discovery cohort analysis, we identified independent genetic variants strongly associated with appendectomy from the UK Biobank (50,105 cases) to serve as instrumental variables (IVs). Summary-level data for gastrointestinal cancers were obtained from the FinnGen study. As the replication cohort, IVs associated with appendectomy were extracted in the FinnGen study (28,601 cases). The data for gastrointestinal cancers were obtained from the UK Biobank. Finally, meta-analyses were conducted to evaluate the combined causal effects of the MR results. We found no causal relationship between appendectomy and gastrointestinal cancers in both the discovery and replication cohorts. Finally, the meta-analysis revealed no causal association between appendectomy and gastrointestinal cancers. Our findings suggest no causal relationship exists between appendectomy and gastrointestinal cancers in the European population. This genetic evidence supports the conclusion from other observational studies that appendectomy does not affect the risk of gastrointestinal cancers in the European population.