Role of intestinal flora in colorectal cancer from the metabolite perspective: a systematic review

Abstract

Colorectal cancer is one of the most common human malignant tumors. Recent research has shown that colorectal cancer is a dysbacteriosis-induced disease; however, the role of intestinal bacteria in colorectal cancer is unclear. This review explores the role of intestinal flora in colorectal cancer. In total, 57 articles were included after identification and screening. The pertinent literature on floral metabolites in colorectal cancer from three metabolic perspectives - including carbohydrate, lipid, and amino acid metabolism - was analyzed. An association network regarding the role of intestinal flora from a metabolic perspective was constructed by analyzing the previous literature to provide direction and insight for further research on intestinal flora in colorectal cancer.

Keywords: amino acids; bacteria; carbohydrate metabolism; colorectal cancer; inflammation; lipid metabolism; microbiology.

Figure 1

Literature search strategy. Notes: The databases “PubMed”, “Embase”, and “Cochrane” were searched for literature published up to August 11, 2017. Forty-two articles were assessed for eligibility after identification and screening. To present a more comprehensive role of flora in colorectal cancer, the flora appearing in the 42 articles were used as the medical subject headings (MeSH) and the pertinent literature was retrieved. A further 15 articles were added after identification and screening.

Figure 2

Network for the intestinal flora and microbial metabolites in colorectal cancer. Notes: An association network of the intestinal flora and microbial metabolites in colorectal cancer from a metabolic perspective was constructed by analyzing the previous literature. The black and blue arrows represent pathogenic bacteria as well as probiotics, respectively. References are located within the square parentheses.