Dysbiotic gut microbiota in pancreatic cancer patients form correlation networks with the oral microbiota and prognostic factors.

Microbiota in the gut and oral cavities of pancreatic cancer (PC) patients differ from those of healthy persons, and bacteria in PC tissues are associated with patients' prognoses. However, the species-level relationship between a dysbiotic gut, oral and cancerous microbiota, and prognostic factors remains unknown. Whole-genome sequencing was performed with fecal DNA from 24 PC patients and 18 healthy persons (HD). Microbial taxonomies, metabolic pathways, and viral presence were determined. DNA was sequenced from saliva and PC tissues, and the association between the gut, oral, and cancer microbiota and prognostic factors in PC patients was analyzed. The PC microbiota were altered from those of the healthy microbiota in terms of microbial taxonomy, pathways and viral presence. Twenty-six species differed significantly between the PC and HD microbiota. Six fecal microbes, including Klebsiella pneumoniae, were associated with an increased hazard of death. In the co-occurrence network, microbes that were abundant in PC patients were plotted close together and formed clusters with prognosis-associated microbes, including K. pneumoniae. Multiple salivary microbes were present in the co-occurrence network. Microbacterium and Stenotrophomonas were detected in the PC tissues and formed a network with the fecal and salivary microbes. The dysbiotic gut microbiota in the PC patients formed a complex network with the oral and cancerous microbiota, and gut microbes abundant in the PC patients were closely linked with poor prognostic factors in the network.