RESUMO
Oral cancer is commonly preceded by premalignant lesions and conditions. The clinician's ability to identify lesions at an increased risk of cancer development is critical for its control. The purpose of this study was to compare the expression of tumor suppressor gene p53, proliferation marker Ki-67, and oncogene c-erbB2 and to evaluate the relevance of their co-expression in the diagnosis of, and prognosis for, oral leukoplakia. In the present study, the expression of biomarkers was studied immunohistochemically in 55 cases of leukoplakia (26 without dysplasia, 29 with dysplasia) and 10 cases of normal epithelia. The Labeling Indices (LI) of p53 and Ki-67 were found to increase significantly with an increase in the grade of dysplasia. A significant correlation was also found between the LI of p53 and that of Ki-67. It was also observed that c-erbB2 expression was only cytoplasmic, indicating incomplete receptor degradation. Hence, it can be concluded from the present study that the increased expression of p53 and Ki-67 with an increase in the grade of dysplasia suggests that their co-expression may be used for the identification of high-risk lesions. Also, c-erbB2 has no pathogenetic role in early carcinogenesis in the studied population, although incomplete receptor degradation, as evidenced by cytoplasmic staining, may indicate an early change.