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Pancreatic cancer is the sixth leading cause of cancer deaths worldwide. Because of limited screening and treatment options, the vast majority of patients diagnosed with the disease are rendered incurable due to it being discovered at an advanced stage.

A new scientific review — recently published in Microbiome — suggests that the microscopic organisms living in a person’s mouth may hold key answers to the development, diagnosis and treatment of pancreatic cancer.

“As the medical and research communities move closer toward the new horizon of precision medicine, the oral microbiome has the opportunity to be on the forefront of clinical innovation in patients with pancreatic cancer,” said study author Jose Trevino, M.D., surgeon-in-chief and member of the Developmental Therapeutics research program at VCU Massey Cancer Center.

The combination of bacteria, fungi, viruses and genes in a person’s mouth is called the oral microbiome. Home to more than 700 different types of bacteria, the oral microbiome is the second largest microbiome in the body behind the intestinal tract, and it plays a significant role in supporting digestion, metabolism and immune function.

Through a comprehensive review — which examined findings from more than 120 global studies — Trevino and a team of researchers from the University of Florida observed that there is a distinct association in patients with pancreatic cancer having a markedly different oral microbiome than the average person. Additionally, the review determined that many of the same disease-driving bacteria seen in the oral cavity have also been identified repeatedly in pancreatic tumors. Although these links have been acknowledged by multiple teams of researchers previously, there is still relatively little known scientifically about why or how these patterns may occur.

There are a number of inherited and environmental factors that can impact the evolution of a person’s oral microbiome, including genetics, race/ethnicity, smoking, socioeconomics and age, among others. Many of these same factors contribute to disparities in pancreatic cancer prevalence, treatment and mortality across different populations, and the study authors suggest that more research should be conducted investigating the potential links between all of these factors.

“With a better understanding of the interplay between the oral microbiome, oral health and pancreatic tumors, more effective screening and treatment strategies may be implemented to improve patient outcomes and reduce health care disparities,” said Trevino, who is also the chair of the Division of Surgical Oncology and the Walter Lawrence, Jr., Distinguished Professor of Oncology at the VCU School of Medicine. “Many unexplored mechanisms linking human diversity in pancreatic cancer and the oral microbiome offer a wide array of opportunities for future intervention.”

Black Americans are diagnosed with pancreatic cancer more often at a later stage and have increased mortality rates compared to other racial and ethnic groups.

“Given the pervasive racial and ethnic disparities in the care and treatment of patients with pancreatic cancer, it is important to recognize the influence of race and ethnicity on the oral microbiome,” Trevino said.

Additionally, smoking serves as the leading risk factor for pancreatic cancer that can be reduced through human decision-making, and it’s also well-documented that cigarette smoking significantly changes the makeup of the oral microbiome. The study authors argue that oral bacteria from smoking may directly or indirectly influence pancreatic cancer development and more research should be conducted exploring this association.

The mouth and the pancreas share similar biological functions, leading the study authors to theorize that changes in the oral microbiome could serve as a model for changes that occur in the pancreas when cancer develops. Assuming there is a correlation between biological changes in the two areas of the body, Trevino and his collaborators propose that the oral microbiome could serve as a non-invasive biomarker for the care and treatment of patients with pancreatic cancer.

Trevino collaborated on this review with Kelly Herremans, M.D., Steven Hughes, M.D., Andrea Riner, M.D., M.P.H., and Miles Cameron of the University of Florida College of Medicine; as well as Kelley McKinley and Eric Triplett, Ph.D., of the University of Florida.

This research was supported, in part, by funding from the Joseph and Ann Matella Fund for Pancreatic Cancer Research Fund, the National Cancer Institute (T32 HG00895), the National Institutes of Health (R01CA242003, R01DK124581), and the University of Florida (U01DK108320).

Written by: Blake Belden