An immunohistochemical study of proliferating cell nuclear antigen (PCNA) and MIB-1 in epithelial hyperplasia and dysplasia of the vocal cords

We investigated the proliferative activities in epithelial hyperplasia and dysplasia of the human vocal cords as precancerous lesions, using immunohistochemical staining with anti-PCNA and MIB-1 (anti-Ki-67) monoclonal antibody. The series for this study consisted of nine patients with hyperplasia, 12 with mild dysplasia, ten with moderate dysplasia, eight with severe dysplasia, eight with vocal cord polyps, and 14 with invasive squamous cell carcinoma. The following results were obtained: 1) The mean PCNA labeling index was 1.12 +/- 1.05 (MEAN +/- STD%) in polyp, 4.88 +/- 2.02 in hyperplasia, 2.76 +/- 1.76 in mild dysplasia, 3.80 +/- 2.03 in moderate dysplasia, 6.12 +/- 3.01 in severe dysplasia, and 19.07 +/- 10.37 in invasive cancer. 2) The mean MIB-1 positive rates were 5.50 +/- 2.47 (MEAN +/- STD%) in polyp, 13.08 +/- 6.86 in hyperplasia, 16.55 +/- 7.34 in mild dysplasia, 15.94 +/- 6.73 in moderate dysplasia, 21.43 +/- 8.16 in severe dysplasia, and 41.48 +/- 14.05 in invasive cancer. In cases of hyperplasia, dysplasia and invasive cancer, PCNA labeling index values and MIB-1 positive rates increased in proportion to the histological atypical grade increasing. Some lesions which recurred or progressed to cancer were found show high expression of PCNA and MIB-1. In cancer cases, there was no significant correlation between the PCNA labeling index, MIB-1 positive rates and either the degree of tumor cell differentiation or the T-classification. There was a positive correlation between the PCNA labeling index and MIB-1 positive rates among all cases. In this study, those cases showing a high PCNA labeling index and/or MIB-1 positive rates may indicate the possibility of recurrence or progression to malignancy in precancerous lesions of the vocal cords.