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

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