A team of scientists in South Africa has discovered that bacteria found in saliva may help identify people at risk of a deadly form of esophageal cancer.
The research, published in Communications Medicine, offers hope that a simple saliva or cheek-swab test might someday help doctors detect warning signs earlier, especially in communities where the disease is common and healthcare access is limited.
The study was carried out by researchers at the Sydney Brenner Institute for Molecular Bioscience at Wits University, together with collaborators from Columbia University in New York.
Esophageal squamous cell carcinoma is one of the most dangerous forms of cancer affecting the digestive system. It develops in the lining of the esophagus, the long tube connecting the throat to the stomach.
One reason the disease is so deadly is that it often causes few obvious symptoms at first. Many patients only seek medical help after they develop severe swallowing problems or significant weight loss. By then, the cancer is frequently advanced and difficult to treat.
In many cases, doctors can only provide palliative care, which focuses on relieving symptoms rather than curing the disease.
The disease is especially common in a high-risk geographic region stretching from parts of China and Iran down eastern Africa, including South Africa.
Researchers have spent decades trying to understand why this pattern exists.
Scientists already know that smoking and heavy alcohol use increase the risk of esophageal squamous cell carcinoma. Other factors linked to higher risk include poverty, rural living, limited education, and exposure to smoke from household fuels used for cooking and heating.
However, these factors alone do not fully explain why some regions have very high cancer rates or why some patients develop the disease without clear risk factors.
Professor Christopher Mathew from Wits University explained that many patients are surprisingly young. The average patient age is about 50 years old, and nearly 18% of patients are diagnosed before age 40.
This unusual age pattern has added to the mystery surrounding the disease.
To search for new clues, researchers turned their attention to the oral microbiome, the huge community of bacteria naturally living inside the mouth.
Scientists are increasingly discovering that bacteria may influence many aspects of human health, including cancer risk, immune function, inflammation, and digestion.
In the study, researchers collected saliva samples from people with esophageal squamous cell carcinoma and compared them with samples from healthy individuals.
Using advanced genetic sequencing and machine-learning technology, the scientists identified major differences between the bacterial communities found in cancer patients and those found in healthy controls.
One bacterium, Fusobacterium nucleatum, stood out because it appeared in larger amounts in cancer patients. Previous research has already linked this bacterium to other cancers, including colorectal cancer.
The scientists developed a prediction model based on saliva bacteria patterns. According to the researchers, the microbiome-based model performed better than models based only on demographic and clinical information.
This suggests saliva bacteria may contain important hidden information about disease processes happening inside the esophagus.
Still, the researchers caution against assuming the bacteria directly cause cancer.
Dr. Wenlong Carl Chen explained that the bacterial changes may simply result from the cancer itself.
As tumors slowly block the esophagus, changes in swallowing and tissue structure may alter the environment in the mouth and throat, leading to shifts in bacterial populations.
Even if the bacteria are only reacting to the disease, they may still serve as useful warning signs.
Researchers believe saliva testing could eventually become a low-cost triage tool to identify people who need further medical evaluation.
Currently, diagnosing esophageal cancer usually requires endoscopy, a procedure where a camera is inserted into the esophagus to examine tissue directly.
While effective, endoscopy can be expensive, uncomfortable, and difficult to access in low-resource healthcare settings.
A saliva-based test could offer a much easier first screening step, especially in high-risk communities.
The researchers are now expanding their work to better understand why the disease develops and whether genetics or environmental exposures may contribute.
One area of interest involves mutation signatures inside tumors. These are patterns of DNA damage that may act like molecular fingerprints, helping scientists trace possible causes such as smoke exposure, pollutants, chemicals, contaminated water, or dietary factors.
The team also plans to study larger groups of patients, including healthy people and patients with non-cancerous esophageal conditions that may also affect swallowing.
This will help determine whether the saliva bacteria patterns specifically point to cancer or more generally reflect problems inside the esophagus.
Professor Michèle Ramsay, Director of the Sydney Brenner Institute for Molecular Bioscience, described the findings as important early groundwork that may eventually lead to practical clinical tools.
If you care about cancer, please read studies about how to fight cancer with these anti-cancer superfoods ,and a berry that can prevent cancer, diabetes and obesity.
For more health information, please see recent studies about how to harness the power of anti-cancer foods and supplements, and cancer-fighting foods and recipes.
Source: Wits University.
