Certain Oral Microbes May Raise Pancreatic Cancer Risk
Research published in September 2025 showed that some of the microbes in our oral microbiome increase the risk of developing pancreatic cancer.
A microbiome is a teeming community of microorganisms like bacteria, viruses, and fungi making their homes in various parts of the human body, our oceans, and even our soil. In recent years, there’s been research showing how human microbiomes, such as the gut microbiome, may influence the development of diseases like inflammatory bowel disease, colorectal cancer, Alzheimer’s disease, and others. Oral bacteria, specifically P. gingivalis, found in the oral microbiome, have even been found in clogged arteries.
This latest study, published online in the journal JAMA Oncology, found that 27 microbes living in the oral microbiome confer a 3.5 times greater risk of developing this cancer. “We all know that pancreatic cancer is highly fatal, often because it is diagnosed too late due to limited early detection. Our initial motivation for this study was could we identify any early detection biomarkers in the oral microbiome that could provide potential screening so more people might be able to undergo surgery, which is the only potential cure for this terrible disease,” explains study co-senior author Jiyoung Ahn, Ph.D., a professor in the Departments of Population Health and Medicine at NYU Grossman School of Medicine, NYU Langone Health, New York City, New York.
Not Just Pancreatic Cancer
The oral microbiome has already been linked to other cancers. In a prior study published September 2024 in JAMA Oncology, researchers from NYU Langone showed the development of head and neck squamous cell cancer was linked to 13 species of bacteria found in the oral cavity.
The oral microbiome has also been associated with pancreatic cancer in prior studies at NYU Langone. For example, researchers there found that P. gingivalis, which is responsible for chronic gum disease, was also associated with an increased risk of pancreatic cancer.
“In our study, we wanted to do a very detailed examination and look at oral fungi as well as bacteria,” explains Ahn, who is also associate director for population sciences at NYU Langone’s Perlmutter Cancer Center. “This wouldn’t have been possible without the incredible advances made in next-generation sequencing. We can get incredibly detailed information quickly due to the technology now available.”
About the New Study
The study followed participants for nine years. Investigators collected oral samples from some 122,000 people aged 50 to 74 years old. To collect these samples, they used two cohorts: the American Cancer Society Cancer Prevention Study-II Nutrition Study Cohort and the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial from the National Cancer Institute. During the nine years of the study, 445 participants were diagnosed with pancreatic cancer.
The oral bacterial and fungal species found in these 445 individuals were then compared with a random sampling of 445 study participants who did not develop pancreatic cancer. Researchers made sure to match for important factors including age, sex, race, ethnicity, and smoking status, all of which influence pancreatic cancer development.
The findings revealed that three periodontal disease pathogens, already known to contribute to periodontal disease, and 13 more oral bacteria were all associated with increased risk of developing pancreatic cancer. Four fungi were also found to increase risk, including a common fungus of the Candida genus. A separate analysis showed that the same Candida fungus was found in oral samples as well as in pancreatic tumors. Candida is a genus of yeasts. It is the most common cause of fungal infections worldwide and the largest genus of medically important yeasts, encompassing about 200 species. The researchers also found eight oral bacteria associated with a decreased risk of developing pancreatic cancer.
The study findings stayed the same after researchers excluded the first three years of follow-up. In a separate analysis, the findings also remained the same when investigators factored in other known risk factors such as smoking, alcohol use, diabetes, and body mass.
In addition, by assessing the makeup of each participant’s oral microbiome, the scientists for the first time developed a tool that could estimate their cancer risk. The tool assigns a microbial risk score based on these pathogens.
According to the researchers, this is largest and most detailed analysis of its kind to date and is also the first to show that oral fungi, specifically Candida, could potentially play a role in pancreatic cancer development.
What’s Next
The next step, of course, is to validate these findings, says Ahn, who notes the study shows correlation not causation. The hope is that a simple test could be developed to screen for pancreatic cancer using the microbial risk score.
Some studies show that poor oral hygiene is strongly linked to higher risks of heart attacks, stroke, and infections like endocarditis. “I believe there is something going on in terms of the oral microbiome and disease development, which in this case, is pancreatic cancer,” Ahn adds. “But we need more information as to exactly how the makeup of the oral microbiome affects the pancreas.”
In the interim the message is clear: brush, floss, rinse, repeat, and visit your dentist regularly for cleanings, she emphasizes. “I think as we move forward it’s going to become very clear that oral health is tied to our overall health,” she adds.
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