Immunological Analysis of Oral Cytobrush Specimens for Early Detection of Oral Cancer Biomarkers: A Comprehensive Review

Early identification of the risk of malignant transformation in oral potentially malignant disorders (OPMDs) is critical for improving outcomes in oral squamous cell carcinoma (OSCC). This comprehensive review examines immunological biomarkers obtained from minimally invasive oral cytobrush (OCB) specimens for the early detection of OSCC within a precision medicine framework. The objectives were to (1) identify and characterise key immunological biomarkers associated with early oral carcinogenesis; (2) evaluate the diagnostic utility of OCB sampling for detecting these biomarkers; and (3) explore the potential of OCB-based profiling to support personalised screening and patient management. The review highlights the potential advantages of OCB compared with conventional diagnostic methods, as reported in the literature, particularly its ability to capture early malignant changes through immunological analysis. Evidence is discussed for biomarker pathways related to cell-cycle and differentiation dysregulation (p53, Ki-67, CKs), inflammation-driven epithelial transformation (IL-1β, IL-6, IL-8, TNF-α), and immune suppression and checkpoint activation (PD-L1, B7-H6). OCB provides reliable and patient-friendly cyto-salivary samples that are suitable for immunological and molecular analyses. Aberrant biomarker expression detected in OCB specimens correlates with epithelial dysplasia and reflects early non-invasive neoplastic transformation, supporting the diagnostic value of integrated biomarker panels. Overall, OCB-based immunoanalysis represents a practical, non-invasive approach for the early detection of OSCC. Emerging technologies, including AI and multi-omics approaches, may further support the precision and predictive values of immunological analysis for OSCC. When combined with relevant biomarker pathways reflecting tumour biology and host immune responses, this strategy could offer a strong foundation for precision-medicine screening. It may also support personalised monitoring in patients with OPMDs.