Introduction: Colorectal Cancer (CRC)
has the highest mortality rate and is recorded to be the third most common cancer
worldwide. The cause of colorectal cancer is multifactorial and multigenic. The
gut has huge commensal microorganisms to maintain homeostasis by regulating various
biological functions such as mucosal barrier, immunity, and metabolic processes.
Accumulating evidence indicates that the gut bacteria play a crucial role in human
health, and the dysbiosis of the gut microbiota is associated with various disorders,
including obesity, diabetes, inflammatory bowel disease, and many types of cancer
especially colorectal cancer. We conducted a systematic review to study the association
between the gut microbiota dysbiosis and its risk for colorectal cancer.
Methods: The search was conducted
in MEDLINE. Titles and abstracts were screened, full-text studied and information
extracted for qualitative synthesis. The exposure was dysbiosis of microbiota in
colon and the outcome was the colorectal cancer.
Results: Our search resulted in 186
studies. By applying several filters needed to our research, finally four studies
were selected for synthesizing the qualitative data. These studies have shown that
some of the gut microbiota such as anaerobic bacteria were significantly increased
in CRC patients.
Conclusion: Although the available data
suggest an association between dysbiosis of gut microbiota and colorectal cancer,
it is limited; hence, more investigations are required to further confirm this.
In the future, targeting the gut microbiota by changing food habits, life style,
antibiotics and probiotics will probably be a powerful weapon in the battle against
Keywords: Colorectal cancer, Dysbiosis,