The Role of the Gut Microbiota in the Development of Colorectal Cancer

Colorectal cancer (CRC) is one of the most common malignant tumours, which development significantly depends on the role of gut microbiota. Here we discuss the possibilities of using individual microorganisms as biomarkers for CRC screening. During the tumorigenesis, a complex interaction is established between the gut microbiome, the tumor microenvironment and the immune system. The composition of the fecal microbiome in patients with CRC is characterized by reduced numbers of protective microorganisms (Clostridiales, Roseburia, Feacalibacterium) and increased diversity of potentially carcinogenic taxa (Bacteroides, Fusobacterium, Campylobacter, Escherichia, Porphyromonas, Prevotella nigrescens, Thermanaerovibrio acidaminovorans). Recent metagenomic studies of stool samples and tumor biopsies indicate an increased representation of oral pathogenic bacteria in the intestinal microbiome in patients with CRC as compared to the control group, suggesting their potential causative role in CRC. The detection of the abovementioned taxa can be used to differentiate individuals with CRC from healthy individuals. Prospects for further research are associated with the identification of microbial CRC markers in prospective epidemiological studies and their applications for non-invasive screening of CRC.