What question did this study set out to answer?

The study aims to evaluate changes in the oral microbiome and its predicted molecular pathways in radiation-treated head and neck cancer patients with oral dryness and taste alterations.

March 7, 2026Open Access

Oral dryness related symptoms in radiation-treated head and neck cancer patients: a pilot study of oral microbiome composition and function

Key Points

The study aims to evaluate changes in the oral microbiome and its predicted molecular pathways in radiation-treated head and neck cancer patients with oral dryness and taste alterations.
Collected saliva and tongue swab samples from head and neck cancer patients at baseline and 18 months post-radiation therapy.
Performed 16S-rRNA gene sequencing to analyze oral microbiome composition.
Classified patients based on symptom severity using a validated ranking scale.
Analyzed diversity using Mann–Whitney U-test and PERMANOVA; identified microbial and pathway associations with MaAsLin2 and ROC curves.
Longitudinal comparisons revealed significant β-diversity changes post-treatment (p < 0.05).
Identified 32 significant taxonomic and 14 metabolic pathway features associated with symptom severity.
Key taxa linked to dysgeusia included Haemophilus parainfluenzae and Gemella sanguinis.
Specific pathways altered included PWY-7431 and KDO-NAGLIPASYN-PWY, correlating with symptom changes.

Abstract

Xerostomia (dry mouth) and dysgeusia (taste changes) are subjective oral symptoms affecting radiation-treated head and neck cancer (HNC) patients. Our objective was to determine longitudinal and cross-sectional changes in oral microbiome profiles and predicted molecular pathways. Saliva and tongue swab samples from HNC patients (N = 25) were collected at baseline (BL) and 18-months (18mos) post-radiation therapy (RT). 16S-rRNA gene V1-V3 next generation sequencing was performed. Subjective xerostomia and dysgeusia scores were determined using EORTC QLQ-H N = 24, N = 48), cross-sectional comparisons included BL high vs low (N = 2 vs 23; N = 4 vs 46) and 18mos high vs low (N = 15 vs 10; N = 30 vs 20). For dysgeusia, longitudinal comparisons included high vs low scores at BL and 18mos (N = 16; N = 32; N = 34, N = 68), and cross-sectional comparisons included BL high vs low (N = 2 vs 23; N = 4 vs 46) and 18mos high vs low (N = 12 vs 13; N = 24 vs 26). α-diversity significance was determined via Mann–Whitney U-test and β-diversity was determined via PERMANOVA. PiCrust2 was used to predict bacterial pathways alterations. MaAsLin2 program was used to determine microbial and pathway associations between timepoint and scoring. ROC curve analysis was used to identify candidate taxa biomarkers. α-diversity did not differ among comparisons. Longitudinal β-diversity comparisons were all significant (p < 0.05). All, but one cross-sectional comparison, were not significant. MaAsLin2 determined 32 significant taxonomic and 14 MetaCyc pathway features. Haemophilus parainfluenzae (padj = 0.01) and Gemella sanguinis (padj = 0.006) were significant taxa distinguishing high and low score dysgeusia groups, per multivariate analysis. Streptococcus salivarius and Ralstonia pickettii were consistently most abundant contributors to pathway alterations. Significant pathways included PWY-7431 (Timepoint; p = 0.001) and KDO-NAGLIPASYN-PWY (BL dysgeusia; p = 0.00035). Oral microbial composition and functional changes occur post-RT that may contribute to xerostomia and dysgeusia. Significant species H. parainfluenzae, G. sanguinis, S. salivarius, and R. pickettii may be involved in xerostomia and taste change post-RT and may be further investigated for possible characterization as biomarkers at the functional level for dry mouth and taste change.

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