Fusobacterium is enriched on the surface and surrounding duodenal mucosa of ampullary carcinoma

Abstract Background and Aims: In colorectal cancer, adenomas develop into carcinomas through the adenoma–carcinoma sequence, which may be triggered by intestinal adherent microbial communities, including Fusobacterium. In this study, we aimed to explore the microbiome in ampullary tumors and clarify its relevance. Methods: Seventeen patients who underwent endoscopic retrograde cholangiopancreatography for ampullary tumors at Nagoya University Hospital from August 2020 to August 2021 were enrolled. The patients were divided into an adenoma group (n = 11) and a carcinoma group (n = 6). Ampullary samples were collected from the tumor surface (tumor samples, TSs) or surrounding normal duodenal mucosa (normal samples, NSs) via brush rubbing and then analyzed. Results: The Shannon α-diversity index was considerably higher in the carcinoma group than in the adenoma group. Fusobacterium, Leptotrichia, Methylorubrum, and Micrococcus were enriched in the TSs of the carcinoma group. The relative abundance of Fusobacteriummarkedly increased with tumor progression. Fusobacterium, Porphyromonas, Granulicatella, and Solobacterium were enriched in the NSs of the carcinoma group, whereas Bergeyella was enriched in those of the adenoma group. Conclusions: Patients with ampullary carcinoma have a greater abundance of Fusobacterium in the tumor and surrounding normal duodenal mucosa than patients with adenoma.