The bacteria found in the tissue samples and oral samples of patients with pancreatic diseases or diseases of the foregut were found to be of similar strains, according to a study that was presented at the 2018 AACR Pancreatic Cancer: Advances in Science and Clinical Care conference in Boston, Massachusetts.1

Every single evaluable subject who was enrolled in the study had similarities between their oral and tissue samples, and 7 common amplicon sequence variants — also known as “features” — were identified in at least half of all of the study participants.

Investigators recruited participants who were undergoing surgery for pancreatic diseases or diseases of the foregut from the Rhode Island Hospital (RIH) from 2014 to 2016 who had both tissue and oral samples to analyze. Researchers performed 16S rRNA gene sequencing on the samples of the 53 patients that were considered evaluable, and they processed all sequencing data in QIIME2.

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Pancreatic tissue samples were harvested from the pancreatic duct, duodenum, normal pancreas, or tumor pancreas, while gastrointestinal tract swabs were extracted from the jejunum, bile duct, or stomach. Oral swabs were collected from the tongue, buccal mucosa, supragingival area, or from the saliva of patients.

From the samples, the researchers identified 4077 and 6556 unique amplicon sequence variants in all of the oral and tissues samples, respectively, and compared the variation in the bacterial strains between sample types. They saw that 1 common feature was shared between the pancreatic tumor samples and all oral samples in 35 participants (approximately 66% of study individuals), and 33 subjects (approximately 62% of patients) had more than 1 common feature between their jejunum swabs and all oral samples. In more than 10 subjects, 3 features were shared between each subject’s oral and pancreas tumor samples.

“Common amplicon sequence variants identified in tissue and oral samples support the hypothesis that oral bacteria could relocate to and overgrow in the jejunum, and possibly translocate to the pancreatic duct to colonize the pancreas,” the researchers concluded.


  1. Zhao N, Chung M, Meier R, at al. Common bacterial strains exist between tissue and oral samples in pancreatic cancer subjects. Presented at AACR Pancreatic Cancer: Advances in Science and Clinical Care; Boston, Massachusetts: September 21-24, 2018. Abstract A006.