A systematic review of the gut microbiome, metabolites, and multi-omics biomarkers across the colorectal cancer care continuum

The gut microbiome and the microbial metabolome contribute to treatment efficacy and treatment outcomes across the cancer care spectrum. This study systematically reviewed the existing literature between 2007 to March 2022 to elucidate the role of gut microbiota-metabolite biomarkers in colorectal cancer (CRC) care and treatment-related outcomes. Using Covidence, all studies identified were screened by title and abstract, followed by a full-text review using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and data extraction. We analysed 13 non-experimental and 9 experimental CRC studies and found that, usually, the α-diversity of the gut microbiome and short-chain fatty acids decreased in CRC patients, while amino acids (e.g. glutamate) increased in CRC patients. Correlations between specific gut microbial taxa and metabolites were identified, with amino acids, fatty acids, and glycerol positively associated with certain gut microbes. Interventions promoting gut microbes and microbial metabolites associated with better health outcomes (e.g. Bifidobacterium, Lactobacillus, butyric acid, and bile acid) can potentially promote treatment efficacy and improve cancer care outcomes. Gut microbial metabolism should be integrated into targeted cancer interventions for CRC patients, given the confirmed role of the gut microbiome and metabolome pathways across the CRC care continuum.