A distinct microbiota signature precedes the clinical diagnosis of hepatocellular carcinoma.

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.