# Changes in Gut Microbiome According to Probiotic Intake in Rectal Cancer Patients Undergoing Diverting Stoma Repair: Study Protocol

## TL;DR

This study explores how probiotic intake affects gut microbiome changes in rectal cancer patients after stoma surgery.

## Contribution

It is the first prospective study to investigate probiotic effects on the resting colon's microbiota after diverting stoma repair.

## Key findings

- Probiotic intake may alter gut microbiota composition in rectal cancer patients.
- Fecal testing will assess microbiota changes at multiple time points.
- The study will evaluate alpha- and beta-diversity using 16S rRNA sequencing.

## Abstract

Background: The gut microbiome is crucial in sustaining intestinal balance and general health. Following rectal cancer surgery, the creation of a diverting stoma to protect the anastomosis results in a defunctioned colon, leading to dysbiosis. The effect of probiotic intake on gut dysbiosis following ileostomy repair remains uncertain. Thus, this study aims to determine the changes in gut microbiota based on the intake of probiotics after diverting stoma repair. Methods: This single-center, parallel, prospective pilot study will include patients with primary rectal cancer planning to undergo a diverting stoma during rectal cancer surgery. The study will comprise 20 patients, with 10 patients receiving synbiotics after stoma repair and 10 patients not receiving probiotics. The primary endpoint is the change in the gut microbiota of the resting colon based on the intake of probiotics, assessed through fecal testing at the following time points: before bowel resection, immediately after diverting stoma repair, and 3 weeks after diverting stoma repair. Changes in gut microbiota will be evaluated using alpha- and beta-diversity analyses based on 16S rRNA sequencing of fecal samples. Discussion: This study is the first prospective cohort trial investigating changes in the gut microbiota of the resting colon based on oral probiotic administration in patients undergoing diverting stoma repair. This trial is anticipated to clarify the impact of probiotic intake in these patients. Trial registration: Clinical Research Information Service (CRIS) of the Republic of Korea, KCT0008392, Registered on 27 April 2023.