Oral fungal profiling and risk of nasopharyngeal carcinoma: a population-based case-control study

Abstract

Background: Dysbiosis of the oral mycobiome has been linked to some diseases, including cancers. However, the role of oral fungal communities in nasopharyngeal carcinoma (NPC) carcinogenesis has not previously been investigated.

Methods: We characterized the oral salivary fungal mycobiome in 476 untreated incident NPC patients and 537 population-based controls using fungal internal transcribed spacer (ITS)-2 sequencing. The relationship between oral fungal mycobiome and the risk of NPC was assessed through bioinformatic and biostatistical analyses.

Findings: We found that lower fungal alpha diversity was associated with an increased odds of NPC [lower vs. higher: observed features (adjusted odds ratio [OR] = 5.81, 95% confidence interval [CI] = 3.60-9.38); Simpson diversity (1.53, 1.03-2.29); Shannon diversity (2.03, 1.35-3.04)]. We also observed a significant difference in global fungal community patterns between cases and controls based on Bray-Curtis dissimilarity (P < 0.001). Carriage of oral fungal species, specifically, Saccharomyces cerevisiae, Candida tropicalis, Lodderomyces elongisporus, Candida albicans, and Fusarium poae, was associated with significantly higher odds of NPC, with ORs ranging from 1.56 to 4.66. Individuals with both low fungal and low bacterial alpha diversity had a profoundly elevated risk of NPC.

Interpretation: Our results suggest that dysbiosis in the oral mycobiome, characterized by a loss of fungal community diversity and overgrowth of several fungal organisms, is associated with a substantially increased risk of NPC.

Funding: This work was funded by the US National Institutes of Health, the Swedish Research Council, the High-level Talents Research Start-up Project of Fujian Medical University, and the China Scholarship Council.

Keywords: Case–control study; Fungi; ITS sequencing; Microbiome; Nasopharyngeal carcinoma; Oral mycobiome.

Fig. 1

Comparison of the oral fungal microbiome between nasopharyngeal carcinoma cases and controls. (a) Cases harboured significantly lower fungal richness (observed amplicon sequence variants [ASVs]) and diversity (Shannon and Simpson indexes) than controls (Wilcoxon tests, P < 0.01). (b) Adonis test (based on Bray–Curtis dissimilarity) adjusted for age, sex, and sequencing run, showed that there was a significant difference in fungal community structure by residential community, disease status, current occupation, Epstein–Barr virus infection status, educational level, tooth loss, cigarette smoking, tooth brushing frequency, and tea drinking. For 9999 permutations, ∗∗∗, FDR-adjusted P < 0.001; ∗∗, P < 0.01; ∗, P < 0.05. (c) Bray–Curtis dissimilarity-based principal coordinates analysis (PCoA) plot revealed a separation in fungal community structure between NPC cases and controls along PC1 and PC2. The axes are labelled with the variation explained, i.e., PC1 explained 16.5% and PC2 explained 7.7% of the variation. (d) The average Bray–Curtis dissimilarity in NPC cases was lower than that in controls (Wilcoxon test, P < 0.001).

Fig. 2

Distribution of relative abundance of predominant oral fungal genera in nasopharyngeal carcinoma cases and controls.

Fig. 3

Differentially abundant oral fungal organisms on corresponding taxonomic levels in nasopharyngeal carcinoma cases and controls. R package ANCOMBC (v. 1.2.2) was used for the differential abundance analysis, adjusted for age, sex, sequencing run, residential community, Epstein–Barr virus infection status, current occupation, educational level, tooth loss, cigarette smoking, tooth brushing frequency, and tea drinking. Horizontal dashed line indicates significance at FDR-adjusted P < 0.05. Only fungal organisms with FDR-adjusted P < 0.05 are shown. Fungal organisms enriched in NPC cases are shown on the left side of the vertical dashed line; those enriched among controls are shown on the right side of the vertical dashed line.