Researchers have identified a potential new method for early cancer detection using a simple oral rinse, which could prove less invasive than current screening techniques for gastrointestinal cancers. The study, conducted in South Korea, explored the connection between microbes found in the mouth and gut, suggesting these oral bacteria could serve as early indicators of gastric and colorectal cancers.
The research team analyzed oral and fecal samples from over 500 individuals, including healthy participants and those with metabolic disorders, as well as patients diagnosed with gastric and colorectal cancer. By employing gene sequencing to study DNA, they measured the mouth-to-feces (MF) index, a metric designed to quantify the similarity between microbial communities in oral and fecal samples.
Their findings indicated a discernible difference in the MF index between cancer patients and healthy individuals. The study revealed distinct microbial 'signatures' in the oral samples of cancer patients. When compared to results from fecal occult blood tests, a standard tool for colon cancer screening, the oral rinse method demonstrated higher sensitivity in detecting gastric and colorectal cancers.
According to the researchers, a non-invasive oral rinse presents a significantly easier and less intrusive alternative to stool tests or colonoscopies for gastrointestinal cancer screenings. Models developed using the oral sample data were able to distinguish between individuals with cancer and healthy participants across various groups.
Sun Ha Jee, a co-corresponding author from Yonsei University, noted that while the presence of oral-associated bacteria in the gut of cancer patients was anticipated, the extent to which these signals varied across disease groups and could be detected in oral samples alone was surprising. The MF index was found to be significantly elevated in patients with gastric or colorectal cancer but not in those with metabolic disorders. This association remained even after accounting for lifestyle factors such as alcohol consumption, exercise, and body mass index.
The researchers plan to conduct further studies to validate these findings in individuals without a prior cancer diagnosis. They also aim to investigate whether the sharing of bacteria between the mouth and gut contributes to cancer development or occurs after cancer has already formed.
Before the method can become widely available, it must successfully navigate clinical trials. However, if the results are positive, this approach could expand access to cancer screening and potentially lead to earlier detection when treatments are most effective.