Altered Nasal Microbiota in Sinonasal Tumors: A Comparative Analysis of Malignant and Benign Sinonasal Tumors

Background Although shifts in nasal microbiota have been well‐documented in inflammatory upper airway conditions, microbiota tumor‐associated alterations remain uncharacterized. This study is the first to compare sinonasal microbiota profiles of patients with malignant tumors (MT), benign tumors (BT), and controls, offering insights into tumor‐associated microbiomes. Methods This prospective, cross‐sectional, observational study assessed intraoperative sinus swabs from 70 adult research participants (MT = 23, BT = 15, control = 32). Sinonasal microbial communities were characterized using 16S rRNA gene amplicon sequencing to determine if microbial community structures differed between groups. Results Tumor‐associated sinonasal microbiota profiles showed clear dysbiosis, with reduced relative abundance of beneficial microbes and increased putative pathogenic taxa. Both MT and BT had significantly lower microbial diversity and distinct compositions compared to controls. MT samples had significantly higher relative abundance of Firmicutes and reduced relative abundance of Actinobacteria. These phylum‐level alterations were accompanied by elevated proinflammatory microbial taxa, paired with reduced relative abundance of keystone, beneficial taxa consistent with healthy nasal microbiomes. Microbial communities in BT and MT samples were similar, but Alcaligenes was more abundant, and Corynebacterium was less abundant in MT than in BT. Conclusion This study observed that sinonasal microbial communities in MT exhibited marked dysbiosis with a reduction in the relative abundance of putative sinonasal commensal taxa compared to controls. These alterations were present to a lesser extent in BT. Future investigations should aim to determine whether these microbial shifts contribute to tumor development or represent secondary effects, with an aim to quantify their impact on outcomes and guide therapeutic strategies.