观察性研究和临床试验的证据表明，肠道微生物群与癌症有关联。然而，肠道微生物群和癌症之间的因果关系有待确定。我们首先基于门、纲、目、科和属级别信息，鉴定出两组肠道微生物群，并从IEU Open GWAS项目获得了癌症数据。然后，我们进行了双样本Mendelian随机化（MR）来确定肠道微生物群是否与八种癌症的因果关系有关。此外，我们还进行了双向MR分析，以检查因果关系的方向。 我们鉴定出11种基因倾向性在肠道微生物群和癌症之间的因果关系，其中包括双歧杆菌属。我们发现有17种强相关性，证明基因倾向性在肠道微生物群和癌症之间的关系紧密相连。此外，我们使用多个数据集发现了24种基因倾向性在肠道微生物群和癌症之间的关联。 我们的MR分析揭示了肠道微生物群与癌症之间的因果关系，并可能有助于为微生物介导的癌症的机制和临床研究提供新的洞见。©2023年，作者。

Evidence from observational studies and clinical trials suggests that the gut microbiota is associated with cancer. However, the causal association between gut microbiota and cancer remains to be determined.We first identified two sets of gut microbiota based on phylum, class, order, family, and genus level information, and cancer data were obtained from the IEU Open GWAS project. We then performed two-sample Mendelian randomisation (MR) to determine whether the gut microbiota is causally associated with eight cancer types. Furthermore, we performed a bi-directional MR analysis to examine the direction of the causal relations.We identified 11 causal relationships between genetic liability in the gut microbiome and cancer, including those involving the genus Bifidobacterium. We found 17 strong associations between genetic liability in the gut microbiome and cancer. Moreover, we found 24 associations between genetic liability in the gut microbiome and cancer using multiple datasets.Our MR analysis revealed that the gut microbiota was causally associated with cancers and may be useful in providing new insights for further mechanistic and clinical studies of microbiota-mediated cancer.© 2023. The Author(s).