Relationship Between Intestinal Flora and Acute Radiation Enteritis in Patients With Advanced Cervical Cancer...

Acute radiation enteritis (RE), particularly diarrhea, remains a major dose-limiting complication in patients with locally advanced cervical cancer (LACC) undergoing concurrent chemoradiotherapy (CCRT). The study investigated the relationship between dynamic intestinal flora alterations and RE-related diarrhea in patients with LACC undergoing CCRT.

This prospective observational cohort study enrolled 83 patients with LACC receiving CCRT in a hospital setting. The patients were categorized into a Mild group (mild diarrhea, adverse events grade < 2, n = 47) and a Severe group (severe diarrhea, grade ≥ 2, n = 36). Fecal samples were collected at baseline (T0), week 4 (T4), and week 8 (T8) after radiation therapy initiation. 16S rRNA sequencing was performed to analyze the microbial composition. Alpha/beta diversity, taxonomic differences, functional pathways, and correlations with clinical indicators were also evaluated.

During CCRT, diarrhea severity peaked at 4 to 5 weeks and gradually decreased in weeks 5 to 8. Significantly decreased alpha diversity at T4 in the Severe group (nadir: 51.10% Firmicutes and 39.10% Bacteroidetes) was partially restored at T8. Beta diversity revealed clustering between the groups at T4. The relative abundances of f__Bacteroidaceae, g__Bacteroides, g__Lachnoclostridium, and s__Bacteroides_vulgatus were higher in the Severe group than in the Mild group at T4, whereas the f__Ruminococcaceae abundance was lower in the Severe group than in the Mild group. g__Bacteroides and g__Lachnoclostridium abundances were significantly and positively correlated with the duration of grade 2 diarrhea. The Severe group demonstrated upregulated amino/nucleotide sugar metabolism and downregulated unsaturated fatty acid biosynthesis. Phenotypic prediction indicated higher pathogenic Bacteroidetes and reduced stress-tolerant Proteobacteria in the Severe group.

Acute RE-related diarrhea severity in patients with cervical cancer undergoing CCRT is associated with intestinal dysbiosis. Severe diarrhea was correlated with reduced alpha diversity, lower Firmicutes/Bacteroidetes ratio, and enriched proinflammatory taxa.