Structural and Functional Alterations of Microbiome in Upper and Lower Respiratory Tract in Patients With NSCLC

Introduction The airway microbiome plays a pivotal role in lung cancer development, but the microbiome characteristics in upper and lower respiratory tract of non-small cell lung cancer (NSCLC) patients remains unclear. Methods This was a prospective case-control study. The study included 60 samples from NSCLC patients and non-cancer controls: 23 sputum (SP) samples (14 NSCLC, 9 controls) and 37 bronchoalveolar lavage fluid (BALF) samples (21 NSCLC, 16 controls). Metagenomic sequencing was performed to characterize microbial composition and diversity, differential taxa, inter-kingdom networks, and functional profiles for bacteria and fungi. Results For bacterial community, BALF samples from NSCLC tend to show higher alpha diversity than that of non-cancer controls (Shannon p = 0.046, Simpson p = 0.089), whereas SP samples from NSCLC show a trend toward lower alpha diversity (Shannon p = 0.053, Simpson p = 0.033). For fungal community, alpha diversity shows no significant difference between NSCLC and non-cancer groups in either SP (Shannon p = 0.250, Simpson p = 0.480) or BALF (Shannon p = 0.800, Simpson p = 0.700) samples. Beta diversity exhibits differences in bacterial community composition between NSCLC and non-cancer controls in both SP (p = 0.018) and BALF samples (p = 0.015), while fungal communities appear relatively stable (p = 0.611 for SP; p = 0.611 for BALF). LEfSe and Random Forest analyses identify bacterium Porphyromonas SGB2015 and fungus Psilocybe cubensis significantly enriched in BALF samples from NSCLC, whereas no species is enriched in SP samples. Cross-kingdom network indicates increased complexity and connectivity in NSCLC-associated microbial communities. Functional analysis shows the enrichment of biosynthetic pathways in SP samples and metabolic pathways in BALF samples from NSCLC. Conclusion These findings suggest that NSCLC may be associated with compositional, structural, and functional alterations of the airway microbiome, with potentially distinct patterns between upper and lower respiratory tract.