A Comparative Analysis of Tissue and Digestive Microbiota Composition in Patients With Oral Squamous Cell Carcinoma

Introduction As the most prevalent malignant tumor in oral cancer, oral squamous cell carcinoma (OSCC) remains incompletely understood, especially its complex interactions with microbiota. This study investigated microbial signatures across tumor tissue and digestive tract niches in patients with OSCC. Methods This retrospective cohort study included 28 patients with OSCC who underwent surgical treatment at a tertiary cancer center between 2019 and 2022, along with 14 healthy controls. 16S rRNA gene sequencing was performed to characterize microbial profiles in tumor tissues, as well as oral and gut samples. Results Tumor tissues exhibited largely similar microbial compositions to adjacent tissues and lymph nodes. However, tumor tissues showed a relatively higher abundance of Fusobacterium and a depletion of Streptococcus . Gut microbiota in patients exhibited dysbiosis, characterized by enrichment of Prevotella , Klebsiella , Lactobacillus , and Streptococcus , while oral microbiota showed enrichment of Streptococcus and Haemophilus . In addition, increased abundance of Lactobacillus in the gut and Bacteroidales in the oral cavity was associated with adverse clinical outcomes (ACO) in OSCC patients. Conclusion The tissues and digestive microbiota of OSCC patients exhibit heterogeneity. These findings suggest that specific microbial signatures may serve as potential biomarkers for disease detection and progression; however, these associations should be interpreted cautiously and require validation in larger cohorts and mechanistic studies.