Microbiota Dysbiosis a Cause of Colorectal Cancer or Not? A Systematic Review

Abstract

Deaths from colorectal cancer (CRC) are still rising, and various links to etiology have been proposed. However, a direct link between microbial dysbiosis and colorectal cancer has not been postulated. This study aimed to identify the role of microbes in the pathogenesis of colorectal cancer. This systematic review was based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A systematic search was done considering papers published over the past 12 years, using PubMed, PubMed Central, Cochrane, Google Scholar, and ScienceDirect databases. Studies were selected based on the following predefined eligibility criteria: English-language systematic reviews, meta-analysis, randomized controlled trials (RCTs), and clinical trials, which included papers on microbes playing roles in colorectal cancer with the derived data transferred to a template. Following this, quality assessment was done using each study's relevant assessment tool. The initial search generated 128 studies. From the study, we found the ratio of Fusobacterium, when compared between healthy and colorectal cancer patients' guts, was the highest, although it was not the most predominant gut organism. Enterotoxigenic Bacteroides fragilis (ETBF), Clostridium and Salmonella, and Peptostreptococcus showed links with colorectal cancer and described pathways that could explain its implication in colorectal cancer. However, overt conclusions cannot be drawn because further research needs to be conducted.Categories: Internal Medicine, Gastroenterology Keywords: microbes or ("microbiota" [all fields] or "microbiome" [all fields]) and ("colorectal cancer" [all fields] or "colorectal carcinogenesis" [all fields] or "colon cancer" [all fields] or "rectal cancer" [all fields]), microbes associated with crc, colerectal carcinogenesis, microbial dysbiosis, microbes and colorectal cancer

Gut Microbiota and Colorectal Cancer: An Umbrella Review of Methodological Trends and Clinical Correlations

“…Out of the 96 reports that were selected for full-text review, 22 of them were not obtainable. We assessed the eligibility of all 74 articles and identified only 20 systematic reviews and meta-analyses that met our inclusion criteria for the final synthesis [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31]. Figure 1 represents the PRISMA flow diagram with a detailed search and selection process overview.…”

The Crucial Roles of Diet, Microbiota, and Postbiotics in Colorectal Cancer

“…In a systematic review including nine studies, organisms associated with CRC were identified as Fusobacterium , Enterotoxigenic Bacteroides fragilis , Clostridium , Salmonella , and Peptostreptococcus [ 73 ]. A meta-analysis of 57 studies demonstrated a higher presence of Fusobacterium nucleatum in tissue samples with CRC tumors [ 74 ].…”

Comedications with Immune Checkpoint Inhibitors: Involvement of the Microbiota, Impact on Efficacy and Practical Implications

“…First of all, dysbiosis could alter the gut mucosa, lead to chronic inflammation, and eventually promote colorectal cancer. Tabowei et al noted in their review the predominant association of Fusobacterium genus with colorectal cancer and its depletion in healthy individuals [ 18 ]. Dysbiosis-associated microbes are thought to activate various immune pathways, including nuclear factor kappa B (NF-κB) dependent signaling, release of inflammatory mediators such as interleukins, or interaction with monocytes, promoting carcinogenesis in the mucosa epithelium [ 18 ].…”

“…Tabowei et al noted in their review the predominant association of Fusobacterium genus with colorectal cancer and its depletion in healthy individuals [ 18 ]. Dysbiosis-associated microbes are thought to activate various immune pathways, including nuclear factor kappa B (NF-κB) dependent signaling, release of inflammatory mediators such as interleukins, or interaction with monocytes, promoting carcinogenesis in the mucosa epithelium [ 18 ]. Likewise, oral microbiota alterations leading to chronic periodontal inflammation have been associated with permanent genetic alterations in epithelial cells and eventually carcinoma development.…”