Simple oral rinse may catch deadly cancer rising in young people early

It’s long been known that the mouth is a window into overall health. 

Mountains of evidence show the vast array of tissue and bacteria in the gums, tongue and teeth can point to a variety of conditions like heart disease, anemia and infections.

Now, a new study suggests these mouth bacteria may be a vital clue in diagnosing cancer, even before typical symptoms begin.

Researchers in South Korea looked at oral and fecal samples from more than 500 people, including both healthy participants and those with metabolic disorders such as diabetes and high blood pressure, as well as gastric and colorectal cancer. 

Using gene sequencing technology to study DNA, the team measured mouth-to-feces (MF) index, which determines similarities between microbes found in oral and fecal samples. 

They then evaluated how well the MF index distinguished between cancer patients and healthy participants. The results revealed a distinct difference, with the cancer patients’ MF index showing specific ‘signatures.’ 

The team then compared the signatures found in the cancer patients to results from fecal occult blood tests – a colon cancer screening tool that analyzes stool samples – and found a higher sensitivity among the oral samples, which were collected via a simple and non-invasive mouth rinse. 

A test with a higher sensitivity signals it is better at detecting a virus or disease, which in this case was gastric and colorectal cancers. 

Additionally, researchers said that models built using the oral samples distinguished patients with cancer from healthy people across multiple groups.  

Researchers said the findings could lead to new, less invasive screening tests for gastrointestinal cancers. 

Co-corresponding author Sun Ha Jee, of Yonsei University, said: ‘The presence of oral-associated bacteria in the gut of patients with cancer was not entirely unexpected.

‘What we had not fully anticipated was how the signal varied across disease groups, how much of it could be detected in oral samples alone, and how strongly it depended on the way microbial features were represented.’

The findings also revealed that the MF index was significantly elevated in patients with gastric or colorectal cancer but not in people with the metabolic disorders. 

Even after accounting for lifestyle factors thought to increase cancer risk, including alcohol consumption, exercise and body mass index, the association between MF index and the cancers remained. 

The researchers are now planning a study to validate their findings in people who have not already been diagnosed with cancer and investigate whether mouth-gut bacteria sharing contributes to cancer development or occurs after cancer has already formed in the body. 

Then, the method and measurements would still need to go through clinical trials before becoming widely available for use.

However, if findings are positive, a non-invasive oral rinse would be much easier to collect and be less invasive than a stool test or colonoscopy, expanding access to screening and potentially catching cancers earlier when they are easier to treat.