Potential Pathogens Associated with Colorectal Cancer

Colorectal cancer (CRC) is a malignancy in which the cells of the colon and rectum grow uncontrollably. This disease initially appears as an adenomatous polyp, which over time turns into an advanced adenoma with high-grade dysplasia and becomes the basis of invasive cancer. The incidence of CRC in the world is very high, it has been reported that this cancer affects between 1 and 2 million new people every year, and CRC is the third most common cancer and the fourth cause of cancer mortality among different cancers. The most important underlying factor for the development of CRC is the age of the person, especially people over 50-years age, who are more susceptible to this cancer with the weakening of the immune system. In addition, it has been observed that in people with inflammatory bowel disease (IBD), CRC increases by about 3.7%. Also, it has been reported that people who have Crohn's disease and suffer from this disease are 2.5% more prone to CRC than people with IBD. In addition to the above, in recent years, it has been found that dysbiosis can be the cause of CRC. Dysbiosis refers to the reduction of microbial diversity and disruption of the balance in the population of beneficial and harmful microorganisms. The disruption of the balance causes an increase in microbial species which play a role in creating a proinflammatory environment. Therefore, dysbiosis can be related to intestinal disorders, including cancer, by disrupting the order in the microbiota population Among the microorganisms that can play a role in CRC due to dysbiosis, one can mention Fusobacterium nucleatum, Escherichia coli, Streptococcus gallolyticus, Helicobacter pylori, Bacteroides fragilis, Enterococcus faecalis, and Salmonella enterica. In the present study, we will investigate the carcinogenic mechanisms of the above-mentioned bacteria, determining the carcinogenic roles of these bacteria