Yonsei University study links oral-gut microbial transmission to cancer

Researchers from Yonsei University have identified that measuring the transmission of microbes from the mouth to the gut can help distinguish patients with gastric or colorectal cancers from healthy individuals. This discovery, published in Cell Host & Microbe, suggests a potentially less-invasive method for gastrointestinal cancer diagnosis and risk stratification.

The study utilized a mouth-to-feces (MF) index, created through 16S ribosomal RNA sequencing, to measure the extent to which identical microbial sequence variants appear in both oral and fecal samples from the same person. In healthy conditions, protective barriers like gastric acid and salivary antimicrobial peptides typically prevent oral bacteria from colonizing the gut. However, the research found that the MF index was significantly elevated in patients with gastric and colorectal cancers, whereas it was not elevated in those with metabolic disorders.

The association remained consistent even when accounting for variables such as body mass index, regular exercise, and alcohol consumption. The findings indicate that the presence of oral microbes in the gut may serve as a quantitative metric for identifying specific gastrointestinal malignancies.