Does toluidine blue detect more oral cancer?

Abstract

Design: A randomised controlled trial.

Intervention: 28,167 individuals aged 15 years or older who were invited participate in a screening programme, 17,890 who lacked oral habits such as cigarette smoking or chewing betel quid were excluded leaving 10,277 eligible individuals. Of these, 2,302 refused to participate leaving a sample of 7,975 for randomisation. The test group gargled with toluidine blue solution while the control group was given a placebo dye of the same colour. Each participant was visually examined by one of six dentists with additional training. The presence of any visible lesion in the oral cavity (e.g. abnormal mucosal lesions related to OPMLs and other suspected lesions such as lichen planus, oral ulcer, hyperkeratosis, candidiasis, etc) was recorded as screen-positive. The screen-positive participants to a specialist were referred to a specialist for a definite clinical diagnosis within 10 to 14 days, to reduce false-positivity, and biopsies were arranged if oral lesions were present. The occurrence of oral cancer, survival status, and causes of death of the studied participants for the entire cohort was obtained from the National Cancer Registry and the National Household Registry until the end of 2004.

Outcome measure: The number of oral lesions, premalignant or not.

Results: In the test group 389 (9.5%) individuals had a positive screen compared with 322 (8.3%) in the control group. Two oral cancers were identified out of those with a positive screen presenting (n=320) for the referral examination from the test group with three oral cancers out of the 293 in those who complied in the control group. There were three oral cancers ascertained by the end of the follow-up among the screen-negatives in each arm (test and control) by the end of the followup period. The numbers of OPMLs in each arm of the study are shown in Table 1.

Conclusions: We demonstrated that using toluidine blue as an adjunctive tool for visual screening can detect significantly more oral submucous fibrosis and slightly more leukoplakia among high-risk individuals with habits of cigarette smoking or betel quid chewing as compared with visual screening alone.