According to the American Cancer Society, colon cancer is the second most common cause of cancer death, and a person has an average lifetime risk of colon cancer of about one in 25. Diagnosing the illness can be disruptive and uncomfortable, since it usually requires a colonoscopy. But the gut microbiome, the community of microbes in the gastrointestinal tract, could help open up a new diagnostic option. Reporting in Cell Host & Microbe, researchers have characterized a vast number of human gut microbes, to identify patterns that can reveal the presence of colon cancer. This dataset could also be used to identify patterns indicating other diseases as well.
This study mined the data of HumGut, a repository of about 490,000 bacterial genomes from over 5,700 human gut samples. This study filtered that data to 3,483 bacterial species, which were classified into subgroups. The researchers tool into account the geographical differences that can arise in human gut microbiomes. They used computational tools to find patterns in the species of gut microbes in the human gut microbiome that could reveal the presence of colorectal cancer.
This work could lead to the creation of a simple and inexpensive colon cancer screening tool. It could also be used to find other screening tools, and reveal novel links between species of gut microbes or the composition of the gut microbiome, and human health or disease.
"Instead of relying on the analysis of the various species composing the microbiota, which does not capture all meaningful differences, or of bacterial strains, which vary greatly from one individual to another, we focused on an intermediate level of the microbiota, the subspecies," noted corresponding study author Mirko Trajkovski, a professor at the University of Geneva. "The subspecies resolution is specific and can capture the differences in how bacteria function and contribute to diseases including cancer, while remaining general enough to detect these changes among different groups of individuals, populations, or countries."
This study can work as a catalog of subspecies in the human gut microbiome that could advance research and could have clinical applications, suggested first study author Matija Trickovic, a graduate student in the Trajkovski lab.
The method created by the researchers was able to diagnose colon cancer 90% of the time, which is almost comparable to the 94% detection rate of colonoscopies. It is also better than any other non-invasive diagnostic method, the investigators noted.
Now, a bit more effort could make this method even more precise and reliable. Although some more research is required, stool samples that are used to analyze the human gut microbiome could one day be used to diagnose colon cancer instead of colonoscopies. This method could also be used for the diagnosis of other disorders.
"The same method could soon be used to develop non-invasive diagnostic tools for a wide range of diseases, all based on a single microbiota analysis," said Trajkovski.
Sources: University of Geneva, Cell Host & Microbe