Intratumor Microbiome Analysis Of Pancreatic Cancer By Analyzing The Fresh Frozen Tissues Obtained By Eus-Fna

Recent studies implied that intratumor microbiome is associated with carciniogenesis, development, prognosis and treatment resistance of pancreatic cancer (PC). While most of previous studies analyze intratumor bacteria in PC by using resected tumor tissues, it is often unable to obtain tumor sample from unresectable advanced PC, and it is unclear whether tiny tissue obtained by endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) is useful for analyzing intratumor microbiome. This study was carried out as a single center, prospective observational study. The patients with PC were eligible for this study. PC tissues were collected from patients who undergo EUS-FNA. Biopsy tissues from the duodenal and gastric mucosa were also collected from the same patients. All samples were immediately stored at -80°C until use. Bacterial DNA was extracted from these specimens and 16S rRNA sequencing was performed. The endpoints of this study were success rate of detecting intratumor bacteria and association between intratumor bacteria and bacteria on the duodenal or gastric mucosa. A total of 90 tissue samples from 30 patients were collected. The median age was 70 years (range 54-86 years), 19/5/6 patients had pancreatic head/body/tail tumor, 16s rRNA sequencing analyses showed that 24 samples (80%) of FNA from pancreatic tumor, 30 samples (100%) of gastric mucosa and 29 samples (97%) of duodenum mucosa could be analyzed. In diversity analyses, PC showed a lower alpha diversity compared to gastric or duodenum tissue. There was a significant difference in microbial structure between PC and duodenum tissue. In PC, dominant phylum was Proteobacteria and dominant genus was Acinetobacter. PC tissues obtained by EUS-FNA were useful for analyzing intratumor microbiome.