Microbial dysbiosis and treatment-related gastrointestinal adverse events in locoregionally advanced nasopharyngeal carcinoma: an exploratory study of the oral and gut microbiome

Gastrointestinal adverse events are frequent during treatment for locoregionally advanced nasopharyngeal carcinoma (LA-NPC) and can impair nutritional status and treatment tolerance. Radiotherapy and chemotherapy may disrupt microbial communities, but whether oral and gut microbiota are associated with treatment-related gastrointestinal adverse events remains unclear. Oral swab and stool samples from 80 patients with LA-NPC were analyzed using 16S rRNA gene sequencing. Associations between treatment-related gastrointestinal adverse events and oral microbial composition were evaluated, together with analyses of microbial functions and gut microbial profiles. Oral microbiota features were then used to develop machine learning models for distinguishing patients with gastrointestinal adverse events. Among 80 patients with LA-NPC, nausea, vomiting, diarrhea, and constipation occurred in 72.5%, 51.3%, 46.3%, and 67.5%, respectively. Oral microbiota analysis showed enrichment of Alloprevotella , Fusobacterium , and Campylobacter in patients with gastrointestinal adverse events or a high symptom burden, whereas Rothia and Streptococcus were enriched in those without events or with a low burden. Predicted oral microbial functions involved propanoate metabolism, lipoic acid metabolism, retinol metabolism, glycan degradation, sphingolipid metabolism, calcium signaling, and lipopolysaccharide biosynthesis. Alterations in specific gut genera, including Helicobacter , Parasutterella , and Anaerotruncus , were also observed. This study identified oral and gut microbial features associated with treatment-related gastrointestinal adverse events in patients with LA-NPC. Oral microbial features showed potential value for classifying gastrointestinal adverse event status during treatment.