Colorectal cancer is the third most common type of cancer in men after lung and prostate cancer, a tumor that arises from the cells that line the inner lining of the colon and rectum. according to public health FranceThere were 43,336 new cases and 17,117 deaths from colorectal cancer in France in 2018. Rarely before the age of 50, colorectal cancer can be effectively treated if caught early.

Hence the need to facilitate early detection. A new study led by the University of Washington School of Medicine (USA) could help. Published in the magazine host cell and microbe, suggests that an increased presence of certain intestinal bacteria would be an indication of a greater likelihood that colon polyps will become cancerous.

A specific strain of common bacteria that causes inflammation

“The increased incidence of colorectal cancer is a major health concern, but little is known about the composition and role of the microbiota associated with precancerous polyps.”, refer to the study authors.

To learn more about the ecology of precancerous polyps, researchers followed 40 patients who underwent routine colon examinations, in addition to colon biopsies. The goal was to collect bacteria near the polyps in order to identify them. All patients ranged in age from 50 to 75 years, and 60% were female.

After analyzing the samples, scientists discovered that a common bacterium, Fragile Bacteroides, non-enterotoxic (not due to enterotoxin), was elevated in mucosal biopsies from patients with polyps.

They also found distinct germline signatures between patients with polyps and those without, and correlated their amount. Fragile B In samples and inflammation of small polyps.

On closer examination, the authors found that Fragile B Of patients with polyps differed in their ability to cause inflammation compared with Fragile B Individuals without polyps.

“The general idea is that most people look at advanced colorectal cancer and think of the microbiome, but it’s hard to say if and when the microbiome has changed, Professor William DePaulo, who led the work, explains. So we looked at the disease earlier and wondered when the microbiome could drive the benign appendix into cancer.”

Biopsies that should target benign tumors

This finding contradicts the idea that there are changes in the composition of the microbiota, with the predominance of pathogenic bacteria, which would be the origin of colorectal cancer.

“What our data suggest is that in order to survive in an environment where metabolic and inflammatory changes occur, a healthy gut and associated bacteria can adapt in a way that helps cause inflammation rather than inhibiting it.”Professor DiPaulo continues.

Not all colon polyps are cancerous: only 5% of them are. But adapting the scans to this finding by taking biopsies near the benign tumors can help search for this particular strain of Fragile B. And this is even before the appearance of cancerous polyps.