A clinical study (NCT06552078) examined how bacteria in the mouth and small intestine are linked to Pancreatic Ductal Adenocarcinoma (PDAC). To ensure accurate results, researchers excluded patients with bile duct blockages so that any microbial changes were related to the cancer itself, not secondary complications.
The study included 24 PDAC patients and 24 healthy people of similar age and sex. Researchers collected saliva and duodenal (small intestine) samples. They found that PDAC patients had lower bacterial diversity in the duodenum, meaning fewer types of bacteria were present. Certain bacteria—such as Solobacterium, Stomatobaculum, and Megasphaera—were more common in cancer patients, while Aggregatibacter was more common in healthy individuals. Differences between mouth and gut bacteria were mainly due to body location rather than disease status.
Importantly, higher bacterial diversity in saliva was strongly linked to longer survival. Patients with low oral bacterial diversity had a median survival of only 2–8 months, while those with higher diversity lived significantly longer. The findings support the idea that oral bacteria may travel to the pancreas and influence tumor growth, and they suggest that a simple saliva test could help predict prognosis in PDAC patients.