For the first time, scientists have identified 27 bacteria and fungi living in our mouths that are implicated in the development of pancreatic cancer. Collectively, housing all of the bad microbes increases one’s risk of the deadly disease by 250% – or 3.5 times higher – compared to the general population.
Researchers from NYU Langone Health and its Perlmutter Cancer Center sampled the saliva of 122,000 healthy US men and women, who took part in the American Cancer Society Cancer Prevention Study II and the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. Samples were collected at baseline, and participants were followed for an average of nine years, with any records of tumors added to the data.
From this large dataset, the researchers identified 445 participants who'd eventually been diagnosed with pancreatic cancer. Their microbial DNA was analyzed and compared with another 445 randomly selected cancer-free people in the trials. They then factored in variables such as age, race and smoking habits.
What they found was that 24 species of bacteria and fungi each either raised or lowered the risk of pancreatic cancer. This was in addition to three types of bacteria that had already been implicated in the development of periodontal disease, the infection that erodes gum tissue and bone around the teeth. People with the specific combo of problematic microbes had a 350% higher risk of developing pancreatic cancer compared with the general population.
And this study is the first to identify a collection of specific microbes that contribute to the cancer risk, and that one fungi – a type of yeast in the genus Candida that lives on the skin and throughout the body – looks to play a specific role. These oral Candida species were also present in the tissue of patients’ pancreatic tumors.
“Our findings provide new insight into the relationship between the oral microbiome and pancreatic cancer,” said study lead author Yixuan Meng, a postdoctoral fellow in the Department of Population Health at the NYU Grossman School of Medicine.
Pancreatic cancer may not be the most common, but it's one of the deadliest. The American Cancer Society found that just 8% of people diagnosed with the disease will live more than five years – this makes it the lowest five-year survival rate of the more than 20 types of common cancers.
Scientists have previously identified a link between the oral microbiome and pancreatic cancer, and theorized that certain bacteria could hitch a ride on swallowed saliva and travels to the organ.
What this research has uncovered is a powerful new tool in advanced cancer diagnostics, enabling clinicians to intervene before tumor development, with treatment focused on correcting the diversity and abundance of species in the microbiome. Right now, there are very few effective screening methods that can assess risk of future disease.
“By profiling bacterial and fungal populations in the mouth, oncologists may be able to flag those most in need of pancreatic cancer screening,” said study co-senior author Jiyoung Ahn, a professor at the NYU Grossman School of Medicine.
While the research only establishes a link between these 27 microbes and pancreatic cancer, it's the most comprehensive understanding we have as to how our mouths contribute to disease elsewhere in the body. More research is needed to unravel what mechanisms may be driving this risk.
“It is clearer than ever that brushing and flossing your teeth may not only help prevent periodontal disease but may also protect against cancer,” said study co-senior author Richard Hayes, a professor in the Department of Population Health.
In 2024, the same team of researchers made another discovery, linking certain oral microbiome species to an increased risk of developing head and neck squamous cell carcinoma – which originates in the cells lining the moist surfaces of the mouth, nose and throat. Next, they'll be looking at whether oral viruses worsen cancer odds, and if certain microbes contribute to the survival chances of those with pancreatic cancer.
The findings are now part of a growing body of evidence linking oral hygiene to poor health outcomes across the body, including Alzheimer's disease and mental health conditions including depression.
The study was published in the journal JAMA Oncology.
Source: NYU Langone Health
