Immediate Multi-Omics Remodelling of Supragingival Plaque After Chemoradiotherapy in Nasopharyngeal Carcinoma

Introduction and aims Radiotherapy for nasopharyngeal carcinoma (NPC) disrupts the oral environment and increases the risk of oral complications, but immediate microbial and metabolic changes in supragingival plaque remain unclear. This study aimed to characterise these changes after treatment and examine associations between microbial composition and metabolic profiles. Methods In this prospective paired study, supragingival plaque was collected from 10 patients with NPC 1 day before radiotherapy and 1 day after radiotherapy completion. All participants received concurrent chemotherapy. Microbial communities were profiled by shotgun metagenomic sequencing and metabolic features by untargeted liquid chromatography–mass spectrometry. Paired comparisons, Procrustes analysis, and correlation analyses assessed treatment-associated changes and cross-omics associations. Results Post-treatment plaque showed reduced Simpson diversity ( P = .037) and altered microbial community structure (PERMANOVA, R² = 0.106, P = .002). Compositional changes included higher Actinomyces relative abundance and lower abundances of several commensal-associated genera. Among 826 annotated metabolic features, 190 met the differential criteria: 150 decreased and 40 increased. The decreased features included 60 lipids and lipid-like molecules, including unsaturated fatty acids and lysophospholipids, whereas selected putative bile-acid-related features increased. Microbial and metabolic profiles were associated across pooled Pre-RT and Post-RT samples (Procrustes correlation = 0.547, P = .041), with positive correlations between several commensal-associated genera and lipid-associated features. Conclusion Supragingival plaque changes following concurrent chemoradiotherapy in patients with NPC included lower relative abundances of several commensal-associated genera, reductions in multiple lipid-associated features, and increases in selected putative bile-acid-related features. Clinical Relevance These early plaque changes warrant longitudinal assessment to determine whether they persist and are associated with subsequent caries or other oral complications.