Comparative microbiome profiling reveals unique signatures in multiple primary lung cancers

Lung cancer is the leading cause of cancer-related mortality worldwide, with a rising incidence of multiple primary lung cancer (MPLC). However, the mechanisms underlying MPLC, including its early clinical diagnosis, pathogenesis and clinical management, remain poorly understood. The intratumoral microbiome is recognized to modulate the immune landscape within the tumor microenvironment (TME), potentially enhancing or suppressing antitumor immunity, thereby influencing tumor progression and therapeutic efficacy. The role of the intratumoral microbiome in MPLC development is an emerging area of research, yet its specific relationship with MPLC remains largely unexplored. This study aims to profile microbial communities in lung cancer tissues and elucidate differences between patients with MPLC and non-MPLC (NMPLC). This study aimed to profile the microbial communities in lung cancer tissues and investigate their potential relationships with MPLC.

16S ribosomal RNA (rRNA) gene sequencing was performed on tumor and adjacent tissues from MPLC and NMPLC patients. Bioinformatics analysis, including alpha diversity (Chao1, Shannon, Simpson), beta diversity (Bray-Curtis, UniFrac), and taxonomic profiling, was performed via QIIME2 and R. Microbial functions were predicted via PICRUSt2, and specific microbial signatures associated with MPLC were identified to explore their potential as biomarkers for early diagnosis and therapeutic strategies.

No significant difference in microbial diversity was observed between tumor and adjacent nontumor tissues. However, tumor tissues in the MPLC group presented higher α diversity than those in the NMPLC group. Functional analysis of the differential microbiota revealed that the tetracycline biosynthesis and naphthalene degradation pathways were upregulated in MPLC, whereas riboflavin metabolism was upregulated in NMPLC. Random forest analysis revealed Faecousia and Burkholderia as key genera with significantly greater abundances in MPLC tumor and paracancerous tissues.

For the first time, we demonstrate a potential association between the microbiota and MPLC, revealing distinct microbial profiles in MPLC tumors and their adjacent tissues compared to those in NMPLC. These findings establish a novel diagnostic framework based on microbial biomarkers that enhances early differentiation between MPLC and NMPLC, thereby facilitating timely and subtype-specific therapeutic decisions.