Study on the Changes of Intestinal Flora in Patients with Colorectal Cancer

Abstract

Objective: To understand the relationship between changes of dominant intestinal flora and the occurrence of colorectal cancer (CRC) by analyzing the stool in normal people and CRC patients, and microbial diversity of cancerous tissues and para-cancerous tissues in patients with CRC. Methods: Stool samples from 44 patients with CRC and 51 healthy adults were collected. The bacteria 16s rDNA were amplified by polymerase chain reaction. The variable regions of 16s rDNA V3–V5 were sequenced. Diversity calculation was performed on the species information to compare the differences of species information among different samples. Results: Chao1 and Shannon index of stool in normal people were lower than those of CRC patients. Firmicutes, Fusobacteria, Synergistetes, Clostridia, Fusobacteriia, Erysipelotrichia, Lachnospiraceae, Ruminococcaceae, Lachnoclostridium, Escherichia and Faecalibaculum in stool sample of CRC patients were higher, while Bacteroidetes, Bacteroidia, Bacteroidaceae, Bacteroides, and Parabacteroides were lower than healthy people. No significant difference in Chao1 or Shannon index between cancerous tissues and para-cancerous tissues in CRC patients. Flavobacteriia, Flavobacteriaceae, Nevskia, Chryseobacterium, and Anaerofustis was lower, yet Xanthomonaaceae was higher in CRC tissues than that of para-cancerous tissues. Conclusions: The complexity of stool in CRC patients is relatively high. There are abundant differences in phyla, class, family, and genus, with no significant difference in microbial diversity between CRC tissues and para-cancerous tissues, except for only a few species.