Efficacy of toluidine blue in the diagnosis and screening of oral cancer and pre-cancer: A systematic review and meta-analysis.

Abstract

The accuracy of toluidine blue (TB) and chemiluminescence for diagnosing oral cancer and pre-cancer was evaluated. Two authors (working independently) comprehensively reviewed six databases (PubMed, Cochrane database, Embase, Web of Science, SCOPUS and Google Scholar) from their dates of inception until March 2020. Oral mucosal disorder, as detected by TB, was compared with that detected by chemiluminescence. True-positive, true-negative, false-positive and false-negative data were extracted for each study. Methodological quality was evaluated using the Quality Assessment of Diagnostic Accuracy Studies tool (ver. 2). The extent of interrater agreement was also assessed. Twenty-nine prospective and retrospective studies were included. The diagnostic odds ratio (DOR) of TB was 7.017 (95% confidence interval [CI], 4.544; 10.836). The area under the summary receiver operating characteristic curve was 0.766. The correlation between the sensitivity and the false-positive rate was 0.196, indicating the absence of heterogeneity. TB exhibited moderate interrater reliability (0.6777; 95% CI, 0.43; 0.7455). Compared with chemiluminescence, as used in nine studies, TB had a lower sensitivity (0.659 vs 0.841), but a higher specificity (0.809 vs 0.345), negative predictive value (0.766 vs 0.690) and DOR (10.565 vs 5.203). Compared with clinical examination, as used in four studies, TB method had a higher sensitivity (0.891 vs 0.891), specificity (0.739 vs 0.634), negative predictive value (0.920 vs 0.714) and DOR (28.491 vs 8.526). Subgroup analysis showed that screening for severe dysplasia or more severe disease was significantly more sensitive, but less specific, than screening for all dysplasias. Although the diagnostic accuracy of TB in the diagnostic work-up of oral cancer and pre-cancer was higher than that of clinical examination, it was not high enough for TB to reliably be used alone. Instead, it should be combined with chemiluminescence or other diagnostic tools.