Malignant transformation of oral epithelial dysplasia: clinicopathological risk factors and outcome analysis in a retrospective cohort of 138 cases.

ABSTRACT

AIMS: To explore the usefulness of a new binary system of grading dysplasia proposed by the World Health Organization and to identify significant risk factors for malignant transformation in a long-term follow-up cohort of patients with oral epithelial dysplasia. METHODS AND RESULTS: A total of 138 patients with histologically confirmed oral dysplasia between 1978 and 2008 were reviewed retrospectively in our department. The mean follow-up period was 5.1 years. Of these dysplasias, 37 (26.8%) developed into cancer, with a mean duration of 4.6 years. Cox regression analysis revealed that high-grade dysplasia was an independent risk factor for transition, but age, gender, lesion site, diet habit, smoking and alcohol intake were not risk factors. High-grade dysplasia was associated with a 2.78-fold (95% confidence interval 1.44-5.38; P = 0.002) increased risk of transition, as compared with low-grade dysplasia. Consistently, high-grade dysplasia had a significantly higher incidence of malignancy than low-grade dysplasia by Kaplan-Meier analysis (log-rank test, P = 0.001). CONCLUSIONS: The utilization of high-grade dysplasia as a significant indicator for evaluating malignant transformation risk in patients with potentially malignant lesions is suggested; this may be helpful to guide treatment selection in clinical practice.