Perioperative altered gut microbiota composition in patients with colorectal cancer: A prospective cohort study

ABSTRACT Objectives: The relationship between surgery and gut microbiota has recently attracted attention, however changes of gut microbiota and the composition are still unclear. The aim of this study was to investigate altered gut microbiota in patients with colorectal cancer in perioperative period. Methods: This prospective, single-center, observational cohort study included 48 patients with colorectal cancer who underwent radical surgery at the Oita University Hospital. Stool samples were collected on the day of and 2 days before surgery, and on postoperative days 1, 3, 7, and after 1 month and 1 year. The primary endpoint of this study was to elucidate gut microbiota composition using 16S rRNA gene sequencing, and the secondary endpoint was to elucidate its association with surgical outcomes. Results: Forty-eight patients were enrolled over a 2-year period from November 2016 to October 2018. Diversity of the gut microbiota decreased to approximately 30% of the preoperative level on the third postoperative day. It recovered to 60% of the preoperative state in the first month and to 80% in the first year. The preoperative gut microbiota was dominated by commensal bacteria (26%), whereas on the first postoperative day, the proportion of facultative anaerobes (46%) increased. Significant differences were not observed between the changes in the gut microbiota and any surgical outcomes. Conclusions: Among gut microbiota composition, facultative anaerobes changed to dominant during the perioperative period of colorectal cancer surgery. The results would provide microbial approaches to maintain gut microbiota composition in practice.