A review of Colorectal Cancer and Intestinal Microbiota

In 2020, around ten million people worldwide were diagnosed with cancer. Being one of the leading causes of death, cancer contributes to a large portion of annual deaths globally. Among them, one of the most common cancers, colorectal cancer, caused around 935 000 deaths in 2020. Cancer is a genetic disease, caused by mutations in oncogenes and tumour suppressor genes. Finding effective diagnosis and treatment methods is one of the most pressing concerns regarding to biomedical science. In the past, the human intestinal microbiota, composed of a huge number of microorganisms including bacteria, fungi and viruses residing in the intestine, has not received much attention and was not considered a factor in disease development. However, increasing evidence have revealed their crucial roles in promoting and suppressing different diseases, including colorectal cancer (CRC), which that is a measure cause of death. The dysbiosis of the intestinal microbiota can result in infection of opportunistic bacteria, gastrointestinal malignancy, metabolic disorders, psychological diseases, and autoimmune diseases. The symbiosis of intestinal microbiota, in contrast, can alter these changes and increase host fitness. Many factors can alter the host's gut microbiota, including sex, age, diet, genetics, geographical conditions including climate and people living around you. This review discusses the different mechanisms of microbiota-induced carcinogenesis of CRC, as well as the potential application of the human intestinal microbiota.