口腔、肠道和肿瘤微生物群落已被认为是胃肠道恶性肿瘤的致癌和进展的重要调节因素。然而，很少有研究关注不同体部位居民微生物的存在和关联。本研究旨在揭示口腔-肠道-肿瘤微生物组的持久性和其在肝细胞癌（HCC）诊断中的表现。本研究包括两个队列：回顾性发现队列，包括364例HBV-HCC患者和160名具有口腔或粪便样本的对照组，前瞻性验证队列，包括91例病例和124名对照，以及48例HBV和39例HBV-肝硬化患者，通过16S rRNA基因测序检查肠道微生物群落。随机森林分析表明，在回顾性队列中，能区分HCC患者和对照组的10个口腔和9个肠道属，在前瞻性匹配的参与者中得到验证，其曲线下面积（AUC）值分别为0.7971和0.8084。当影响因子分类合并后，一致分类器的AUC增加至0.9405。与非胎盘球蛋白（AFP）血清水平相结合，性能继续提高至0.9811。具体而言，由链球菌代表的微生物生物标志物在疾病转化过程中呈持续上升的趋势。此外，在肝肿瘤和非肿瘤组织中，存在多种优势微生物物种，经荧光原位杂交（FISH）和5R 16S rRNA基因测序确认。总的来说，基于口腔、肠道和肿瘤微生物群落的发现提供了一种可靠的HCC早期诊断方法。

Oral, gut, and tumor microbiota have been implicated as important regulators in the carcinogenesis and progression of gastrointestinal malignancies. However, few studies focused on the existence and association of resident microbes within different body regions. Herein, we aim to reveal the durability of the oral-gut-tumor microbiome and its diagnostic performance in hepatocellular carcinoma (HCC). Our study included two cohorts: a retrospective discovery cohort of 364 HBV-HCC patients and 160 controls with oral or fecal samples, a prospective validation cohort of 91 cases, and 124 controls for matching samples, as well as 48 HBV, and 39 HBV-cirrhosis patients for gut microbial patterns examined by 16S rRNA gene sequencing. With the random forest analysis, 10 oral and 9 gut genera that could distinguish HCC from controls in the retrospective cohort were validated among the prospective matching participants, with area under the curve (AUC) values of 0.7971 and 0.8084, respectively. When influential taxa were merged, the AUC of the consistent classifier increased to 0.9405. The performance continued to improve to 0.9811 when combined with serum levels of alpha-fetoprotein (AFP). Specifically, microbial biomarkers represented by Streptococcus displayed a constantly increasing trend during the disease transition. Furthermore, the presence of several dominant microbiota species was confirmed in hepatic tumor and non-tumor tissues with fluorescence in situ hybridization (FISH) and 5 R 16S rRNA gene sequencing. Overall, our findings based on the oral-gut-tumor microbiota provide a reliable approach for the early detection of HCC.