Colorectal cancer (CRC) remains the third most common cancer worldwide, with a growing incidence among young adults. Multiple studies have presented associations between the gut microbiome and CRC, suggesting a link with cancer risk. Although CRC microbiome studies continue to profile larger patient cohorts with increasingly economical and rapid DNA sequencing platforms, few common associations with CRC have been identified, in part due to limitations in taxonomic resolution and differences in analysis methodologies. Complementing these taxonomic studies is the newly recognized phenomenon that bacterial organization into biofilm structures in the mucus layer of the gut is a consistent feature of right-sided (proximal), but not left-sided (distal) colorectal cancer. In the present study, we performed 16S rRNA gene amplicon sequencing and biofilm quantification in a new cohort of patients from Malaysia, followed by a meta-analysis of eleven additional publicly available data sets on stool and tissue-based CRC microbiota using Resphera Insight, a high-resolution analytical tool for species-level characterization. Results from the Malaysian cohort and the expanded meta-analysis confirm that CRC tissues are enriched for invasive biofilms (particularly on right-sided tumors), a symbiont with capacity for tumorigenesis (Bacteroides fragilis), and oral pathogens including Fusobacterium nucleatum, Parvimonas micra, and Peptostreptococcus stomatis. Considered in aggregate, species from the Human Oral Microbiome Database are highly enriched in CRC. Although no detected microbial feature was universally present, their substantial overlap and combined prevalence supports a role for the gut microbiota in a significant percentage (>80%) of CRC cases.

结直肠癌（CRC）仍然是全球第三大常见癌症，在年轻人中发病率不断上升。多项研究表明肠道微生物组与CRC之间存在关联，表明与癌症风险之间存在关联。尽管CRC微生物组研究继续通过越来越经济和快速的DNA测序平台对更大的患者人群进行分析，但与CRC的常见关联却很少，部分是由于分类学分辨率的限制和分析方法的差异。与这些分类学研究相辅相成的是一种新近认识到的现象，即细菌组织成肠道粘液层生物膜结构是右侧（近端）结肠癌的特征，而不是左侧（远端）结直肠癌的特征。在目前的研究中，我们在来自马来西亚的新患者队列中进行了16S rRNA基因扩增子测序和生物膜定量，然后使用高分辨率分析工具Resphera Insight对11个其他基于粪便和组织的CRC菌群的其他公开可用数据集进行了荟萃分析。用于物种级别的表征。马来西亚队列研究的结果和扩展的荟萃分析证实，CRC组织富含侵入性生物膜（特别是在右侧肿瘤上），这是一种具有肿瘤发生能力的共生体（脆弱的拟杆菌（Bacteroides fragilis）），以及口腔病原体，包括核梭形杆菌（Fusobacter nucleatum），帕尔克莫纳斯（Parvimonas micra）和气孔杆菌（Peptostreptococcus stomatis）。从总体上考虑，人类口腔微生物组数据库中的物种在CRC中高度丰富。尽管没有检测到的微生物特征普遍存在，但它们的实质性重叠和合并患病率在很大比例（> 80％）的CRC病例中支持了肠道菌群的作用。