Abstract

Salivary microbiome profiling may represent a promising non-invasive approach for characterizing OSCC-associated microbial patterns and longitudinal microbiome dynamics during patient management. This exploratory pilot study aimed to longitudinally assess salivary microbiota profiles in patients with oral squamous cell carcinoma (OSCC) before and after tumor resection using Oxford Nanopore Technology. Unstimulated saliva samples were collected from 16 patients with OSCC at two time points (before and after tumor resection) and from 10 OSCC-free reference subjects. Microbial DNA was extracted using the QIAamp DNA Blood Kit (QIAGEN GmbH, Hilden, Germany) and subjected to long read metagenomic sequencing using the Oxford Nanopore MinION platform (v. 20.06.4, Oxford Nanopore Technologies, Oxford, UK). Taxonomic profiling was performed to longitudinally characterize salivary microbiota composition within patients and to provide descriptive comparisons with the OSCC-free reference cohort. Longitudinal analysis identified differences in salivary microbiota profiles between pre- and post-resection samples. Before surgery, an increased relative abundance of Neisseria subflava and Leptotrichia buccalis was observed. Post-surgical samples showed higher levels of Glaesserella parasuis, Streptomyces anulatus, and Lactobacillus species. Distinct microbial patterns were also descriptively observed between OSCC patients and OSCC-free controls, suggesting disease-associated dysbiosis. This exploratory longitudinal pilot study suggests differences in salivary microbiota profiles between samples collected before and after tumor resection in patients with OSCC, including changes in taxonomic composition and reduced alpha diversity. Given the limited sample size and the potential influence of unmeasured perioperative factors, these findings should be considered hypothesis-generating. Larger, well-controlled longitudinal studies incorporating standardized oral health assessment and detailed perioperative metadata are required to clarify the biological and clinical relevance of these observations.

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