Cyclooxygenase-2 and Ki67 Expression in Oral Leukoplakia: a Clinicopathological Study

OBJECTIVES Oral leukoplakia is a precancerous lesion of the oral mucosa. The upregulation of Ki67 and cyclooxygenase-2 has been reported in both dysplastic and non-dysplastic tissues. The aim of this clinicopathological study was to investigate the prognostic value of Ki67 and cyclooxygenase-2 expression for oral leukoplakia. MATERIAL AND METHODS A total of 50 samples were investigated and the study group consisted of 30 oral leukoplakia samples. Samples of 10 intact oral mucosa and 10 squamous cell carcinoma were included as negative and positive control groups, respectively. Epithelial dysplasia was defined as oral intraepithelial neoplasia (OIN) and classified into subgroups 1 - 3. Tissue samples were assessed immunohistochemically for Ki67 and cyclooxygenase-2 expression. Clinicopathological correlations of oral leukoplakia patients were also investigated. RESULTS All OIN 3 patients were non-smokers (P < 0.05), and homogeneous oral leukoplakia lesions also presented OIN. Both cyclooxygenase-2 and Ki67 expression increased with the severity of lesions, which defined different subgroups (P < 0.05), except there was no significant difference between the hyperkeratosis and OIN groups for Ki67 expression. CONCLUSIONS Cyclooxygenase-2 and Ki67 expression may have a prognostic value for the malignant transformation of oral leukoplakia.