How effective is toluidine blue for screening and diagnosis of oral cancer and premalignant lesions?

Design A systematic review and bivariate meta-analysis was designed to determine the efficacy of toluidine blue (TB) in the screening and diagnosis of oral cancer and premalignant lesions. Six databases were reviewed independently by two authors to identify relevant studies.Case selection Inclusion criteria comprised prospective or retrospective studies comparing TB with chemiluminescence or clinical examination, which incorporated sensitivity and specificity analyses. Studies regarding diagnosis of non-oral tumours were excluded, as well as case reports and review articles.Data analysis Diagnostic accuracy was analysed using diagnostic odds ratio (DOR) with 95% confidence intervals (CI). Summary receiver operating characteristic (SROC) curves and the inter-rater agreement were also analysed. Cohen's kappa coefficient and Fisher z-values were used to estimate reliability and stabilise variance. Homogeneity analyses were performed using the Q statistic. Forest plots were drawn for the sensitivity, specificity, negative predictive values, and SROC curves.Results Twenty-nine studies comprising 1,921 participants were included in the meta-analysis. The DOR of TB was 7.017 (95% CI, 4.544; 10.836). Nine studies compared TB with chemiluminescence; TB had a lower sensitivity but a higher specificity. Compared with clinical examination in four studies, TB had a higher sensitivity and specificity. TB has a sensitivity of 73% and specificity of 69%, and was found to be more sensitive in severe dysplasia but more specific in benign lesions.Conclusions The diagnostic accuracy of TB for oral cancer or premalignant lesions is greater than clinical examination alone; however, it is not reliable enough for TB to be used as a screening method in isolation. TB is a diagnostic aid that can be recommended in adjunct with chemiluminescence or other techniques.