Diagnostic performance of methylene blue vital staining for early detection of oral epithelial dysplasia and carcinoma in high-risk populations: A meta-analysis.

Abstract

e18008 Background: Early detection of oral precancer and cancer significantly improves prognosis, yet reliable and affordable screening tools remain limited in low-resource settings. Methylene blue staining is a simple, low-cost adjunctive technique proposed for identifying early mucosal lesions. This diagnostic test accuracy (DTA) meta-analysis evaluated its pooled sensitivity, specificity, and overall discriminative performance. Methods: A systematic search of databases was performed through November 2025. Studies assessing methylene blue staining for detecting oral precancer or cancer, using histopathology as the reference standard, and providing sufficient data to derive 2×2 contingency tables were included. Pooled sensitivity and specificity were calculated using a bivariate random-effects model. Statistical analyses were performed using Stata 17.0, R 4.5.2, and Meta-DiSc 2.0. Results: A total of nine studies were included. The pooled sensitivity of methylene blue staining was 88.5% (95% CI; 79.2%-94.0%). The pooled specificity was 56.1% (95% CI; 36.1%-74.3%), reflecting moderate discrimination and a notable false-positive rate. The SROC curve showed an AUC of 0.846, supporting good overall diagnostic performance. The pooled positive likelihood ratio (LR+) was 2.02, while the negative likelihood ratio ratio (LR-) was 0.20. Substantial heterogeneity was observed for both sensitivity (I² = 78.9%) and specificity (I² = 86.9%), likely due to differences in lesion stage, staining technique, and study design. Conclusions: Methylene blue is a highly sensitive and moderately accurate adjunctive tool for early detection of oral precancer and cancer, particularly valuable in low-resource settings. However, limited specificity suggests it should complement, not replace, definitive diagnostic evaluation. To improve its clinical application, more standardized, prospective research is required.