Growing research has examined the association of oral microbiome with pancreatic cancer risk, but results have been inconsistent. Our previous study showed that bacterial taxa known to inhabit the oral cavity were common in the pancreas microbiome, and that bacterial DNA profiles in the pancreas were similar to those in the duodenum tissue of the same subjects regardless of disease state. These data suggest that bacteria may be migrating from oral into the gut and pancreas. We collected oral swabs and at least one pancreatic tissue or intestinal samples from subjects who underwent surgery for pancreatic diseases or diseases and characterized 16S ribosomal RNA genes using high-throughput DNA sequencing. We then quantified bacterial communities (Amplicon Sequence Variant level) at different body sites, investigated their co-abundance patterns, and analyzed the correlations between microbiome at oral sites and that in pancreatic tissue and intestinal samples using concordance statistics and Pairwise Stratified Association (PASTA) testing. The present analysis included 52 subjects (46% with pancreatic cancer; aged from 31 to 86 years old) contributing a total 324 samples. We identified a total of 73 unique Amplicon Sequence Variants (ASVs) that were shared between oral and pancreatic or intestinal samples. Accounting for pairing and within-subject correlation, 7 ASVs showed significant concordance (Kappa statistics) and 5 ASVs exhibited significant or marginally significant PASTA between oral samples and pancreatic tissue or intestinal samples. Of these, our PASTA analyses identified two specific bacterial species (Gemella morbillorum and Fusobacterium nucleatum subsp. vincentii) that showed consistent presence or absence patterns between oral and intestinal or pancreatic samples. Lastly, our microbial co-abundance analyses showed several distinct ASVs clusters and complex correlation-networks between ASV clusters in buccal, saliva, duodenum, jejunum, and pancreatic tumor samples. Oral, intestinal, and pancreatic microbiomes are correlated. Bacteria of oral origin exhibit co-abundance relationships and demonstrate complex correlation patterns in the intestinal and pancreatic tumor samples. Growing evidence has shown that bacterial species may survive, decline, and adapt as interdependent functional groups. Future studies should aim to uncover the co-abundance of specific microbial communities for studying etiology of microbiota-driven carcinogenesis in prospective and longitudinal studies.

Citation Format: Mei Chung, Naisi Zhao, Richard Meier, Devein C. Koestler, Erika Del Castillo, Guojun Wu, Bruce J. Paster, Kevin Charpentier, Jacques Izard, Karl T. Kelsey, Dominique S. Michaud. Oral, intestinal, and pancreatic microbiomes are correlated and exhibit co-abundance in patients with pancreatic cancer and other gastrointestinal diseases [abstract]. In: Proceedings of the AACR Special Conference on the Microbiome, Viruses, and Cancer; 2020 Feb 21-24; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2020;80(8 Suppl):Abstract nr B07.