Colorectal cancer (CRC) accounts for about 10% of all new cancer cases globally. Located at close proximity to the colorectal epithelium, the gut microbiota comprises a large population of microorganisms that interact with host cells to regulate many physiological processes, such as energy harvest, metabolism and immune response. Sequencing studies have revealed microbial compositional and ecological changes in patients with CRC, whereas functional studies in animal models have pinpointed the roles of several bacteria in colorectal carcinogenesis, including Fusobacterium nucleatum and certain strains of Escherichia coli and Bacteroides fragilis. These findings give new opportunities to take advantage of our knowledge on the gut microbiota for clinical applications, such as gut microbiota analysis as screening, prognostic or predictive biomarkers, or modulating microorganisms to prevent cancer, augment therapies and reduce adverse effects of treatment. This Review aims to provide an overview and discussion of the gut microbiota in colorectal neoplasia, including relevant mechanisms in microbiota-related carcinogenesis, the potential of utilizing the microbiota as CRC biomarkers, and the prospect for modulating the microbiota for CRC prevention or treatment. These scientific findings will pave the way to clinically translate the use of gut microbiota for CRC in the near future.

结直肠癌（CRC）占全球所有新癌症病例的约10％。肠道菌群紧邻大肠上皮，包含大量微生物，这些微生物与宿主细胞相互作用以调节许多生理过程，例如能量收集，代谢和免疫反应。测序研究揭示了CRC患者的微生物组成和生态变化，而动物模型的功能研究指出了几种细菌在大肠癌发生中的作用，包括核梭形杆菌和某些菌株的大肠杆菌和脆弱的拟杆菌（Bacteroides fragilis）。这些发现为利用我们对肠道菌群的知识提供了新的机会，可用于临床应用，例如肠道菌群分析，如筛选，预后或预测性生物标志物，或调节微生物以预防癌症，增强疗法并减少治疗的不良影响。这篇综述旨在概述和讨论大肠肿瘤中肠道菌群，包括微生物群相关致癌作用的相关机制，利用该菌群作为CRC生物标志物的潜力以及调节该菌群用于CRC预防或治疗的前景。这些科学发现将为在不久的将来临床翻译肠道菌群用于CRC铺平道路。