Gut Microbiota and Colorectal Cancer

Abstract

Background: Colorectal cancer (CRC) is a leading cause of cancer-related mortality worldwide whose incidence has increased rapidly in recent years. There is growing evidence that the complex gut microbiota community plays an important role in the development of intestinal tumorigenesis. Summary: This review aimed to explore the correlation between gut microbiota and CRC as well as to identify the pathogens and their metabolites that affect CRC and the potential models of gut microbiota action. It promotes our understanding of the correlation between gut microbiota and CRC. Key Message: Our knowledge of the risk factors associated with gut microbiota for CRC development, as well as of the mechanism how intestinal bacteria act on colorectal tumorigenesis, has improved, leading to a better understanding of the correlation between gut microbiota and CRC. Practical Implications: The intestinal microbiota community has a close relationship with CRC by influencing the mechanism of the body and by regulating the physiological function of the colorectum and even the entire digestive system. Gut microbiota have been linked to CRC based upon their toxic and genotoxic metabolites production by fermentation of dietary ingredients. These metabolites could bind specific intestinal cell surface receptors and subsequently affect intracellular signal transduction. The mechanisms by which gut microbiota affect CRC development include the ‘Alpha-bug' model, the ‘driver-passenger' model and the ‘intestinal microbiota adaptions' model. This review promotes our understanding of the correlation between gut microbiota and CRC.

Food groups and risk of colorectal cancer

“…Besides the fact that mutagens link the association between red or processed red meat and risk of CRC, recent research indicated that the intestinal microbiota (e.g., Bacteroides ) might be relevant for colorectal carcinogenesis. However, more studies are needed that investigate interactions and potential mechanisms between dietary factors and gut microbiota regarding CRC risk …”

“…However, more studies are needed that investigate interactions and potential mechanisms between dietary factors and gut microbiota regarding CRC risk. 45,46 Our systematic review has several strengths, and also limitations. The first limitation is that dietary behavior is often associated with other factors related to risk of CRC, such as physical activity, smoking, alcohol intake and obesity, and it might be possible that these factors affect our observations.…”

Obesity and cancer: inflammation bridges the two

“…A growing amount of evidence has linked colorectal cancer to intestinal microbiota and dysfunction of the intestinal barrier [87,88]. Studies have also shown that altered gut microbiota is present in patients with adenomas of the colon, suggesting a role for dysbiosis in the early stages of colorectal cancer development [89,90].…”

Cecal microbiota association with tumor load in a colorectal cancer mouse model

“…The driver–passenger hypothesis states that the gut microbiota association with CRC is mainly a succession process, where bacteria that are favored by the tumorigenic environment later replace the initial CRC inducers [4]. Finally, the microbiota adaptation hypothesis suggests that the association between the gut microbiota and CRC is mainly an adaptation of the gut microbiota, as a consequence of the changed environment during CRC development [5]. …”