Colonic Microbiome and Cancers
The human large gut or the colon is a common site for cancer. New cases of colorectal cancer are found
in more than a quarter million people each year, globally, making it one of the most common cancers worldwide.
Early detection and treatment offers a 70%-90% cure rate, so much research is focused on the early detection of colon cancers.
The human intestine houses over 100 billion bacteria, with the largest proportion of these bacteria being present in the colon. Thus, the colon is one of the most densely populated microbial ecosystems in the human body.
Under normal physiological states, the colonic microbiome serves important immunological, structural and metabolic functions including, of course digestion.
Advanced scientific research can now explain the genetic landscape of the colonic microbiome.
The role of the gut microbiome in colorectal cancers has long been the area of interest to scientists to explore the association of a particular individual and the risk for developing cancers over time.
It is well known that molecular changes in multiple genes underlie the development of piling up (hyperplastic) of surface cells and lead to progression to a polyp formation and then to cancer.
Experiments and gene-based models of colorectal cancer formation have confirmed that mutations in human genes influence polyps and cancer development.
In the colon, the surface cells change their character to stop cell death and grow abnormally before spreading. The same concept can be applied to the colonic microbiome consisting of various groups of bacteria, bacteriophages, viruses, and fungi.
These microbes can be considered as gene networks that can also be transformed and cause cancer formation..
Molecular changes in the genes allow for this transformation by altering the genetic stability, metabolism, and the response of the immune system to progress to the development of cancers. Thus, the colonic microbiome is now considered a prime suspect for triggering the initiation and/or progression of colonic cancer formation.
Other studies have found a link between gut bacteria, which are important contributors to bile acid metabolism, which in turn is linked to a high fat diet.
Therefore specific species, microbialgroups, and microbial metabolites generated from ingested foodstuffs are all potential targets for decreasing or increasing cancer risk and perhaps even for diagnosis, treatment stratification, and therapy.
A potential area to focus could be to determine whether early antibiotic treatment targeted towards the above pathogens has any effect on the development of colorectal cancers.
It appears then that the development of colorectal cancers in humans is multifactorial. Current studies have examined the evidence and concluded that the colonic microbiome may be a significant contributing factor.
The bacteria play crucial roles in cancer formation although more studies are needed to further clarify their specific roles.
Detection of certain bacterial concentrations within stool or biopsies of polyps and cancer could assist us to screen and help identify higher risk patients.
So far the gold standard for screening colon cancer I san endoscopic examination starting at 50 years of age ,once 2-3 years or earlier for people with family history of colon cancer.
Bacterial assays that are not so expensive are needed to facilitate the integration of the colonic microbiome into routine testing for the detection of colorectal cancers by way of bringing patients for an earlier endoscopy.