Characteristics of fecal gut microbiota in patients with colorectal cancer at different stages and different sites

Numerous studies have revealed that the gut microbiota serves an important role in the pathogenesis of colorectal cancer (CRC). The present study aimed to investigate the populations present in the gut microbiota in patients with CRC of different stages and at different sites. Fecal samples were obtained from 67 CRC patients and 30 healthy controls, which were analyzed by sequencing the V3-V4 region of the 16S rRNA gene. Increased diversity of the fecal gut microbiota in patients with CRC was reported compared with the healthy controls. In the present study, at the genus level, the relative abundances of <i>Prevotella, Collinsella</i> and <i>Peptostreptococcus</i> in the gut microbiota of CRC patients were substantially increased compared with healthy controls, while the relative abundance of <i>Escherichia-Shigella</i> was significantly lower. In addition, differences in the fecal gut microbiota were also compared between patients with stage I-IV CRC and healthy controls. The results revealed that the abundances of the genera <i>Peptostreptococcus, Collinsella</i> and <i>Ruminococcus</i> were significantly increased in patients with CRC stage I compared with the healthy controls, while <i>Alistipes</i> was enriched in patients with stage III CRC compared with patients with stage IV. Furthermore, the present study reported that the genera <i>Veillonella</i> and <i>Coprobacter</i> were more abundant in the proximal segments than in the distal segments of the colon. In conclusion, despite the low number of samples employed in the present study, a signature of genera indicating dysbiosis of the gut microbiota of patients with stage I-IV CRC patients was proposed, which may provide insight into the mechanisms underlying the progression of CRC. These findings are also valuable for developing novel fecal diagnostic methods and therapeutic strategies for the treatment of CRC.