Gut microbiota shifts in patients with gastric cancer in perioperative period.

Gastric cancer (GC) is one of the common malignant tumors in China, with a high morbidity and mortality. With the development and application of high-throughput sequencing technologies and metagenomics, a great quantity of studies have shown that gastrointestinal microbiota is closely related to digestive system diseases. Although some studies have reported the effect of long-term follow-up after subtotal gastrectomy on intestinal flora changes in patients with GC. However, the features of gut microbiota and their shifts in patients with GC in perioperative period remain unclear.This study was designed to characterize fecal microbiota shifts of the patients with GC before and after the radical distal gastrectomy (RDG) during their hospital staying periods. Furthermore, fecal microbiota was also compared between the GC patients and healthy individuals.Patients who were diagnosed with advanced gastric adenocarcinoma at distal stomach were enrolled in the study. The bacterial burden within fecal samples was determined using quantitative polymerase chain reaction. To analyze the diversity and composition of gut microbiota from fecal DNA of 20 GC patients and 22 healthy controls, amplicons of the 16S rRNA gene from all subjects were pyrosequenced. To study gut microbiota shifts, the fecal microbiota from 6 GC patients before and after RDG was detected and subsequently analyzed. Short-chain fatty acids were also detected by chromatography spectrometer in these 6 GC patients.RDG had a moderate effect on bacterial richness and evenness, but had pronounced effects on the composition of postoperative gut microbiota compared with preoperative group. The relative abundances of genera Akkermansia, Esherichia/Shigella, Lactobacillus, and Dialister were significant changed in perioperative period. Remarkably, higher abundances of Escherichia/Shigella, Veillonella, and Clostridium XVIII and lower abundances of Bacteroides were observed in gut microbiota of overall GC patients compared to healthy controls.This study is the first study to characterize the altered gut microbiota within fecal samples from GC patients during perioperative period, and provide a new insights on such microbial perturbations as a potential effector of perioperative period phenotype. Further research must validate these discoveries and may evaluate targeted microbiota shifts to improve outcomes in GC patients.