Role of the Microbiome in the Formation and Development of Colorectal Cancer.

The clinical, histopathological, and molecular characteristics of colorectal cancer vary considerably. Factors associated with the heterogeneity of this disease and with understanding the effects of heterogeneity on disease progression and response to therapy are critical for the better stratification of patients and the development of new therapeutic methods. Although studies have focused mainly on tumor molecular profiling, current molecular predictive and prognostic factors are relevant to specific groups of colorectal cancer patients and are mostly used to predict the applicability of targeted biological agents rather than to predict their benefits. Molecular profiling fails to capture aspects important for tumor growth and aggressiveness, including the tumor microenvironment. The gut microbiome, consisting of specific communities of all commensal, symbiotic, and pathogenic microorganisms, has been shown to have a significant impact on the development of many diseases, including Crohns disease, type II diabetes, and obesity. Recent studies have indicated that long-term dysbiosis of the intestinal microflora can influence the development and progression of colorectal cancer, as well as tumor aggressiveness and response to treatment.This review article summarizes current knowledge of the gut microbiome in colorectal cancer, including the various mechanisms by which the gut microbiome affects the intestinal wall, thereby contributing to the development and progression of colorectal cancer. This work was supported by Ministry of Health of the Czech Republic (project AZV 16-31966A), project of Ministry of Education, Youth and Sports of the Czech Republic - NPU I - LO1413 a Ministry of Health of the Czech Republic - RVO (MMCI, 00209805). The authors declare they have no potential conflicts of interest concerning drugs, products, or services used in the study. The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers. Submitted: 15. 4. 2019 Accepted: 17. 6. 2019.