Siavash Safiee - Cancer research center, Shahid Beheshti Uneversity of Medical Science, Tehran, Iran
Fatemeh Hadavandsiri - Cancer research center, Shahid Beheshti Uneversity of Medical Science, Tehran, Iran
Mohammad Esmaeil Akbari - Cancer research center, Shahid Beheshti Uneversity of Medical Science, Tehran, Iran

Introduction: Colorectal cancer is the third most commonly occurring sub-group of cancers [۱]. The gut microbiome hypothesized to play a role in colorectal cancer development. This systematic review focuses on differences between gut microbiome in patients diagnosed with colorectal cancer at a specific clinical stage, using fecal samples to reach a conclusion on the association between gut microbiome and the progression of colorectal cancer. Methods: In the present review, databases such as Medline, Web of Science, and Scopus were comprehensively searched for published articles until May ۲۰۲۱. The keywords used were stage, gut microbiome, and colorectal cancer. Full text research studies in English language which were dealing with the effect of gut microbiome on development of colorectal cancer were included in the study. Results: The review comprised of ۱۱ publications. All the studies identified that microbiome dysbiosis is associated with colorectal cancer. Almost all studies have shown that changes were associated with stages of colorectal cancer. Furthermore, it has been shown that there is a significant separation in microbiome between early (I-II stages) and late stage (III-IV) disease and Fusobacteriom, Bacteroides and Clostridium genera were the most common. During progression of the colorectal cancer, bacterial and viral diversity reduced, whereas diversity of fungi increased from early to late-stage disease. Conclusion: To determine the correlation between gut microbiome and colorectal cancer to use as a tool to innovate new strategies in cancer therapy, more studies that focus on specific stages of colorectal cancer patients and use comparable and reproducible methods are needed.

Gut microbiome, colorectal cancer, stages