Characterization of the gut microbiota in patients with stage III colorectal cancer: A case-control study

Aim To conduct a case-control study (pilot study) in Africa (Mali) in comparing the gut microbiota of patients with stage III colorectal cancer (CRC) using next-generation sequencing. Methods Shotgun sequencing was performed to characterize participants’ fecal microbiota using Illumina’s HiSeq platform. This case-control study involved newly diagnosed CRC patients (n = 23) prior to any treatment initiation, and unrelated healthy controls (n = 24) to elucidate their microbial diversity and relative abundance. Results The findings revealed that the gut microbiota in CRC and in healthy were significantly distinctive according to the PERMANOVA test (R² = 0.132, P = 0.001), and the alpha-diversity was significantly lower in CRC. Beta-diversity, based on principal coordinate analysis, showed a distinct taxonomy between the CRC and the healthy. Levels of Pseudomonadota , Escherichia , Citrobacter freundii , Klebsiella sp. LTGPAF-6F , Escherichia albertii, Escherichia coli, Caudovirales , Apicomplexa, and Verrucomicrobiota populations were significantly elevated in CRC. The major metabolic pathways with higher relative abundance levels found in CRC compared to healthy were related to HEMESYN2-PWY: heme biosynthesis II (anaerobic) , PWY-5154:L-arginine biosynthesis III (via N-acetyl-L-citrulline) , FUC-RHAMCAT-PWY: superpathway of fucose and rhamnose degradation , ECASYN-PWY: enterobacterial common antigen biosynthesis, ENTBACSYN-PWY: enterobactin biosynthesis, and AEROBACTINSYN-PWY: aerobactin biosynthesis. Conclusion Distinct gut microbiome profiles between healthy and CRC were observed. In particular, the findings showed a significant reduction in microbial diversity in stage III CRC. This study provides initial metagenomic data on Malian patients with CRC. It will be used to create a larger cohort to better understand the relationship between CRC and the gut microbiota in the Malian CRC population.