Multi-Niche Microbial Profiling in Papillary Thyroid Carcinoma and Thyroid Nodules: Linking Oral, Gut, and Tissue Microbiota.

Purpose: Microbial communities have emerged as crucial regulators in the initiation and progression of thyroid cancer. However, most studies focus on single microbial sources, and the interplay between microbes across different ecological niches and their impact on thyroid carcinogenesis are largely unknown. Patients and Methods: In this study, we collected tissue, oral, and fecal samples from 32 patients with benign thyroid nodules (BTN) and 32 patients with papillary thyroid carcinoma (PTC). The oral and fecal samples were subjected to 16S rRNA sequencing, while the tissue samples were analyzed using 5R 16S sequencing to comprehensively characterize the microbial communities. Results: Clustering analysis using the Dirichlet Multinomial Mixture model with Laplace approximation identified two distinct oral microbial community types (O_1 and O_2) and three fecal types (F_1, F_2, and F_3). Microbial diversity patterns in thyroid tissues mirrored those observed in oral and fecal samples, suggesting potential microbial translocation or systemic interactions. Inflammatory markers were significantly elevated in PTC patients relative to BTN controls. Notably, the genus Veillonella, a potential anti-tumor biomarker, was significantly reduced in PTC samples across niches. Conclusion: This study highlights the pivotal role of oral and intestinal microbiota in PTC development, emphasizing the interplay between microbial composition, inflammatory processes, and immune regulation in tumor progression. The discovery of