Presenter(s)
D. Zuo1, Y. Zhu2, D. Li3, and Y. Zhang1; 1Department of Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China, 2Department of Clinical Laboratory, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China, 3State Key Laboratory of Molecular Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
Purpose/Objective(s): We hypothesized that the intratumoral microbiome of hypopharyngeal cancer differs from adjacent normal mucosa and that specific microbial signatures associate with disease extent and overall survival (OS) in a large paired-biopsy cohort.
Materials/Methods: In a retrospective single-institution cohort, 92 patients underwent pretreatment endoscopic biopsies yielding paired tumor and adjacent normal mucosa samples. 16S rRNA sequencing evaluated alpha diversity (Chao1, Simpson) using paired Wilcoxon signed-rank tests and beta diversity using Bray–Curtis dissimilarity and PERMANOVA (999 permutations). LEfSe identified differential taxa. OS was analyzed in 52 patients with complete clinical outcome data. Howardella status was predefined as tumor relative abundance >0 (positive) vs 0 (negative). Survival was assessed using Kaplan–Meier/log-rank and Cox proportional hazards models, with sensitivity analyses adjusting for age and T category.
Results: Tumors exhibited lower alpha diversity than paired normal mucosa (Chao1 P=0.00047; Simpson P=0.021). Community composition differed between paired tumor and normal tissues (PERMANOVA R²=0.0219, P=0.001). Intratumoral beta diversity correlated with T category (T1–2 n=13 vs T3–4 n=44; P=0.025) and nodal status (N0 n=7 vs N+ n=51; P=0.037). Tumors were enriched in Fusobacterium, Capnocytophaga, and Prevotellaceae, whereas normal mucosa was enriched in Streptococcus and Actinobacillus. Advanced T category (T3–4) and N+ status correlated with Prevotella and Streptococcus enrichment, respectively. In the OS subset, Howardella-positive patients had worse OS (log-rank P=0.0074; univariable HR 2.41, 95% CI 1.24–4.69, P=0.0093; age-adjusted HR 2.10, P=0.037). This association attenuated after adjusting for T category (HR 1.36, 95% CI 0.55–3.41, P=0.499) and was not significant in T3–4-only analyses (P=0.316), suggesting confounding by tumor extent.
Conclusion: In this retrospective cohort of 92 paired biopsies, hypopharyngeal tumors harbored distinct, lower-diversity microbiomes compared with adjacent normal mucosa. Intratumoral microbial composition correlated with T category and nodal status. Howardella detection was associated with inferior OS in unadjusted analyses, but this association attenuated after accounting for T category.