Study: Bacteria and fungi in the mouth may help identify those at risk for pancreatic cancer

RELEVANCE

Most relevant for: People concerned about their risk of pancreatic cancer.

It may also be relevant for:

• healthy people with average cancer risk

Relevance: Medium

Strength of Science: Medium

Research Timeline: Human Research

More rating details

What is this study about?

This study looked at whether the types of bacteria and fungi in the mouth (the oral microbiome) indicate an increased risk of pancreatic cancer.

Why is this study important?

Pancreatic cancer often goes undetected until it is advanced and hard to treat. Only 13% of people with pancreatic cancer live more than five years after being diagnosed. Known risk factors include smoking, being overweight, inflammation of the pancreas (called pancreatitis), a family history of pancreatic cancer and certain inherited genetic mutations. However, these risk factors explain only one-third of cases. Previous research suggests gum disease may also signal the risk of pancreatic cancer.

Scientists are trying to identify ways to detect pancreatic cancer more quickly by gaining a better understanding of the possible link between the oral microbiome and cancer risk. The oral microbiome includes bacteria and fungi that are normally found in the mouth. Each person’s microbiome is unique, and even though many of these microorganisms normally support overall health, some bacteria and fungi in the microbiome can be harmful and may lead to various health problems.

Some harmful oral bacteria, like Porphyromonas gingivalis (P. gingivalis, the bacteria that cause gum disease or gingivitis) are more common among people with pancreatic cancer.  

This study aimed to answer: Could the mix of bacteria and fungi in the mouth help predict who is more likely to develop pancreatic cancer?

Study details & findings

Researchers used data gathered from 122,000 participants in two large studies in the United States. The participants provided samples similar to a mouth rinse which were tested for different types of bacteria and fungi. The study followed participants for nearly nine years and compared the findings of those who eventually developed pancreatic cancer with those who did not.

During that nine-year follow-up period, 445 study participants developed pancreatic cancer. For each of those 445 people, researchers identified a study participant with similar attributes (same age, sex, race, smoking history, etc.) who did not develop cancer and compared the microbiome samples between the two groups.

The study found that participants who developed pancreatic cancer within the studied period had different microbes present in their mouths than those who did not develop pancreatic cancer. This suggests that the makeup of a person’s oral microbiome may be an indicator of pancreatic cancer risk.

Additional key findings from the study include:

• Specific bacteria and fungi linked to pancreatic cancer: People with certain harmful bacteria and fungi in their mouths, especially those linked to gum disease, were more likely to develop pancreatic cancer. These included:
  • the bacteria P. gingivalis, E. nodatum and P. micra.
  • the fungus Candida (a type of yeast)
• Microbial risk score findings: Researchers combined the risk levels from all bacteria and fungi into a single “microbial risk score”. When comparing these scores, they found that people with higher scores had more than three times the risk of developing pancreatic cancer than those with lower scores.
  •  The lifetime risk of pancreatic cancer for people in the general population is about 1%, so for those with high microbial risk scores, that risk is about 3%.
• Additional factors influencing pancreatic cancer risk: Participants who were diagnosed with pancreatic cancer differed from those who were not in several ways, including: weight, diabetes, smoking habits, alcohol use and family history of pancreatic cancer. To make sure that the pancreatic cancer diagnosis was not affected by these factors, the researchers used specific statistical methods to rule out the impact of weight, diabetes, smoking and alcohol use. They did not rule out the impact of family history of pancreatic cancer. Researchers did not know if this apparent increased risk was due, in part, to an inherited mutation known to increase the risk of pancreatic cancer. It is unclear if these results would be similar for people at high risk due to an inherited mutation. They also did not evaluate other factors that could contribute to pancreatic cancer risk, like diet or dental history.
• Additional limitations: The researchers relied on a single collection of an oral wash sample among all participants. Oral microbiome may change prior to cancer diagnosis. Most participants (92 percent) were white. The results may not be generalizable.

What does this mean for me?

This study suggests that changes in the oral microbiome —especially increases in certain bacteria and fungi—may signal which people have a higher risk of pancreatic cancer. Although results from this study offer helpful insights, the tests used to collect and observe the oral microbiome are investigational and not available clinically yet.

In the future, looking at the oral microbiome may be a helpful method to identify those at higher risk of pancreatic cancer. Although this study was not designed to determine if the oral microbiome contributes to the development of pancreatic cancer, it does establish a correlation between the oral microbiome and pancreatic cancer. Even though more research is needed to fully understand whether the oral microbiome reflects cancer risk, taking care of your oral health can improve your general health.

Reference

Meng Y, Wu F, Kwak S, et al. Oral Bacterial and Fungal Microbiome and Subsequent Risk for Pancreatic Cancer. JAMA Oncology. 2025. doi:10.1001/jamaoncol.2025.3377.

Disclosure: FORCE receives funding from industry sponsors, including companies that manufacture cancer drugs, tests and devices. All XRAYS articles are written independently of any sponsor and are reviewed by members of our Scientific Advisory Board prior to publication to assure scientific integrity.

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posted 11/24/25