Prevalence and associations between gut bacteria with colorectal cancer: A study on colorectal cancer patients at Military Hospital 175, Vietnam

Abstract Objectives Recent studies have suggested that commensal bacteria may play a role in the progression of colorectal cancer (CRC). Therefore, this study aimed to evaluate the abundance of Fusobacterium nucleatum, Bacteroides fragilis, Akkermansia muciniphila, and Escherichia coli, and to examine their associations with CRC progression and clinicopathological features in Vietnamese patients. Methods Clinicopathological features of CRC were assessed using histopathological examination, and the presence and relative quantification of the targeted bacteria and gene mutations were determined using real-time PCR assay in 149 tissue samples from CRC and 109 colorectal polyp samples. Results The prevalences of Fusobacterium nucleatum, Bacteroides fragilis, and Escherichia coli in CRC tissues were higher compared to those in colorectal polyp tissues (68.5% vs. 46.8%; p < 0.001); (71.1% vs. 31.2%; p < 0.001); and (46.3% vs. 11.0%; p < 0.001), respectively. The relative quantification and co-infection rates of these species in CRC tissues were significantly greater (p < 0.001). Furthermore, these bacteria were associated with an increased risk of polyp-to-CRC progression (p ≤ 0.001). Fusobacterium nucleatum was associated with an increased risk of ulcerative - exophytic lesion (p = 0.011), and G12C/R/V/A, G13C (p = 0.021), and Q61L/R/H (p = 0.03) variants of KRAS mutations. Conclusion Fusobacterium nucleatum, Bacteroides fragilis, and Escherichia coli associated with polyp-to-CRC progression. However, among these bacteria, only Fusobacterium nucleatum showed a significant relationship with clinicopathological features, being associated with ulcerative–exophytic lesions and KRAS mutations at variants G12C/R/V/A, G13C, and Q61L/R/H.