Examining the Research Gap in Salivary Biomarkers for Oral Cancer Detection in Nigerian Populations

Salivary biomarkers offer a non-invasive, point-of-care approach to oral cancer detection that could revolutionise early diagnosis in low-resource Nigerian settings, yet biomarker validation in Nigerian oral cancer populations is virtually absent from the literature. This study examined the research gap in salivary biomarker utility for oral cancer detection in Nigerian populations through systematic review and original exploratory research. A systematic scoping review of ten databases identified 187 publications from 2018 to 2024 on salivary biomarkers for oral cancer globally, of which zero specifically validated biomarkers in Nigerian patient populations. Original exploratory research collected stimulated whole saliva from 30 oral squamous cell carcinoma patients, 30 leukoplakia patients, and 30 healthy controls at UNTH Enugu. Salivary IL-6, IL-8, VEGF, and MMP-9 were quantified by ELISA. IL-8 showed the largest fold-increase in OSCC versus healthy controls (mean 4.8-fold, p < 0.001) and the highest diagnostic sensitivity (80.0 percent at a defined cut-off). IL-6 showed significant elevation in leukoplakia, suggesting potential for pre-malignant detection. Combined IL-8 and IL-6 improved sensitivity to 86.7 percent. The study identifies three critical research gaps: larger validation studies in diverse Nigerian populations, development of point-of-care salivary testing platforms for low-resource settings, and longitudinal studies tracking biomarker change in leukoplakia-to-malignancy progression. Recommendations include NCI-Africa collaboration for multi-site validation. Keywords: salivary biomarkers, oral cancer detection, Nigeria, IL-8, diagnostic sensitivity