Oral, intestinal, and pancreatic microbiomes are correlated and exhibit co-abundance in patients with pancreatic cancer and other gastrointestinal diseases.

Oral microbiota are believed to play important roles in systemic diseases, including cancer. We collected oral swabs and at least one pancreatic tissue or intestinal samples from 52 subjects, and characterized 16S ribosomal RNA genes using high-throughput DNA sequencing in 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 Pairwise Stratified Association (PASTA) between oral samples and pancreatic tissue or intestinal samples. Of these, two specific bacterial species ( Gemella morbillorum and Fusobacterium nucleatum subsp. vincentii ) 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. Toghether, our findings suggest that oral, intestinal, and pancreatic microbiomes are correlated and bacteria of oral origin exhibit co-abundance relationships and demonstrate complex correlation patterns in the intestinal and pancreatic tumor samples. Future prospective studies should aim to uncover the co-abundance of specific microbial communities for studying etiology of microbiota-driven carcinogenesis. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement The research reported in this publication was supported by the NIH/NCI grants R01 CA166150 and P30 CA168524. ### Author Declarations All relevant ethical guidelines have been followed; any necessary IRB and/or ethics committee approvals have been obtained and details of the IRB/oversight body are included in the manuscript. Yes All necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes Sequence data have been deposited in Sequence Read Archive (SRA)