Analysis of 16S rRNA to evaluate taxonomic differences between salivary and intratumoral microbiota in patients affected by oral squamous cell carcinoma: a single-center pilot study

Background Advancements in DNA sequencing technology have facilitated the assessment of the connection between the oral microbiome and various diseases. The aim of the present study was to investigate the differences between salivary and intratumoral microbiota composition in patients affected by oral squamous cell carcinoma (OSCC). Methods Unstimulated saliva and intratumoral fresh biopsy samples were collected. DNA was extracted using the QIAamp PowerFecal Pro, and next-generation sequencing was performed using the MiSeq Illumina device. Results A total of 12 patients were enrolled, of whom 7 were diagnosed with OSCC and five were OSCC-free, comprising the control group, including healthy patients and those affected by oral potentially malignant diseases (OPMDs). In the OSCC group, four were male and three were female, with a mean age of 58.4 ± 11.5 years; in the control OSCC-free group, four were male and one was female, with a mean age of 59.4 ± 18.3 years. The masticatory mucosa was the most affected OSCC site (42.8%), followed by the floor of the mouth (28.6%), the border of the tongue (14.3%), and the palate (14.3%). Compared to controls, the OSCC group exhibited an enrichment of bacteria such as Fusobacterium nucleatum in the tumor tissue, alongside a distinct salivary profile characterized by the enrichment of the Neisseria genus and a consequent depletion of Streptococcus. Conclusions Despite the limited sample size of this pilot study, we observed that the oral microbiota differs significantly depending on both the patient’s clinical status (OSCC vs. OSCC-free) and the specific sampling site (tumor tissue vs. saliva). A potential association between oral dysbiosis and OSCC onset may provide a new target for future validation and early diagnosis.