Analysis of gut and mucosal microbiomes in patients with extrahepatic cholangiocarcinoma.

620 Background: Cholangiocarcinoma is an aggressive malignancy with a poor prognosis. While gut microbial dysbiosis is linked to various diseases, including biliary disorders and cancer, its association with cholangiocarcinoma remains unclear. Methods: This study compared the mucosal and gut microbiomes of patients with extrahepatic cholangiocarcinoma (n = 21) to those with cholecystitis (n = 21) and healthy individuals (n = 28). Mucosal microbiomes were collected from cancer lesions and gallbladders, with fecal samples obtained from 31 participants. The 16S rRNA gene (V3 and V4 region) was sequenced using the Illumina MiSeq platform and analyzed with QIIME 2. Results: 16S rRNA sequencing revealed Proteobacteria as the dominant taxon in the cancer cohort, with Klebsiella, Aeromonas, Staphylococcus, Fusobacterium, and Haemophilus also enriched. In contrast, Firmicutes dominated in the cholecystitis and control cohorts. β-diversity analysis highlighted significant differences between cohorts. Elevated levels of bile acids, particularly chenodeoxycholic acid and ursodeoxycholic acid, were observed in the cancer cohort and positively correlated with Proteobacteria, Aeromonas, Enterobacter, and Enterococcus. Conclusions: These findings suggest that microbiome dysbiosis contributes to cholangiocarcinoma development.