# Comparison of Pre‐ and Postoperative Gut Microbiota Diversity in Patients With Rectal Cancer Undergoing Stoma Creation and Closure

## TL;DR

Creating and closing a temporary stoma during rectal cancer surgery reduces gut microbiota diversity and shifts its composition toward harmful bacteria, with effects lasting at least six months.

## Contribution

This study reveals that temporary stoma procedures cause persistent gut microbiota dysbiosis in rectal cancer patients.

## Key findings

- Stoma patients showed decreased alpha and beta diversity six months post-surgery.
- Pathogenic genera like Enterococcus increased, while beneficial genera like Anaerostipes decreased.
- Non-stoma patients had no significant changes in microbiota diversity or composition.

## Abstract

To investigate the impact of temporary stoma creation and its subsequent closure on gut microbiota composition and diversity in patients undergoing rectal cancer surgery.

Nineteen patients with primary rectal cancer who underwent curative surgery were enrolled and divided into two groups: stoma (n = 10, all underwent temporary ileostomy) and non‐stoma (n = 9). Fecal samples were collected preoperatively and 6 months postoperatively. Gut microbiota composition was analyzed using 16S rRNA gene sequencing. Alpha diversity (observed operational taxonomic units and Shannon index) and beta diversity (UniFrac distances) were compared between time points. Taxonomic shift was identified using Linear discriminant analysis Effect Size (LEfSe).

In the stoma group, alpha diversity significantly decreased after surgery (p = 0.049), and beta diversity analyses revealed significant changes in microbial composition (PERMANOVA; unweighted p = 0.026; weighted p = 0.046). LEfSe analysis identified an increased abundance of potentially pathogenic genera (e.g., Enterococcus and Eggerthella) and a decreased abundance of short‐chain fatty acid‐producing genera (e.g., Megamonas and Anaerostipes). These changes persisted for at least 6 months after stoma closure. In contrast, the non‐stoma group showed no significant alterations in microbial diversity or composition over time.

Temporary stoma creation in rectal cancer surgery induces persistent alterations in gut microbiota; these alterations are characterized by reduced diversity and a shift toward a dysbiotic profile with increased pathogenic and decreased beneficial taxa. These findings highlight the potential need for microbiota‐targeted strategies to mitigate long‐term dysbiosis in patients undergoing stoma‐related procedures.

We investigated the impact of temporary stoma creation and closure on gut microbiota diversity in rectal cancer patients. 16S rRNA sequencing revealed that microbial diversity significantly decreased postoperatively in the stoma group but remained stable in non‐stoma patients.