Intestinal microbiota shows potential as diagnostic tool
10 Sep 2019
The composition of intestinal microbiology can influence chances of developing bowel cancer, researchers have found.
By assessing results from prospective and case–control studies, a team at the Federal University of Viçosa, Brazil, identified microbe characteristics that can increase chances of developing disease, as well as other microbe groups that can even slow down cancer progression.
“Intestinal microbiota of individuals with colorectal cancer usually contains a greater proportion of bacteria responsible for gastrointestinal tract inflammatory diseases, as well as bacteria that produce toxins and carcinogenic metabolites,” the research paper, published in the Journal of Medical Microbiology, says.
The research means intestinal microbiota could be used as a diagnostic tool, although further studies that associate microbial composition with a specific disease will be needed first.
Dr Sandra dos Reis, who led the research, said: “New forms of prevention and treatment for certain diseases can be developed using the intestinal microbiota, since the composition of this microbiota can be changed by a number of factors such as diet, the use of probiotics, prebiotics and antimicrobials among others.”
The research identified three main ways intestinal microbiota can increase the likelihood of cancer developing. Firstly, inflammatory diseases that are triggered by gut bacteria interacting with the immune system. People with high levels of Fusobacterium in the gut, for example, were 3.5 times more likely to develop adenomas in the colon.
Secondly, when toxin-producing bacteria release molecules that bind to cells that line the colon. These bacteria then change the way cells behave and divide – sometimes becoming cancerous. Examples include Bacteroides fragilis, E. coli, Klebsiella pneumoniae and Enterobacter aerogenes.
Thirdly, when bacteria – including B. fragilis, E. coli and Clostridium – produce carcinogenic metabolites break down food, drugs or compounds produced by the host.
The research also said higher numbers of probiotic bacteria and bacteria that produce butyric acid may reduce the likelihood of cancer developing in the lower intestine or reduce tumour growth.
“Butyric acid may be able to inhibit tumour development through different mechanisms,” Dr dos Reis said. “Thus, when abundant in the intestinal microbiota, butyric-acid producing bacteria would exert a protective effect against colorectal cancer.”