Evaluation of Ki67, p16 and CK17 Markers in Differentiating Cervical Intraepithelial Neoplasia and Benign Lesions

BACKGROUND Cervical intraepithelial neoplasia (CIN) is a premalignant lesion capable of progressing to cervical cancer. Despite the existing well-defined criteria, the histomorphologic diagnosis is subject to high rates of discordance among pathologists. The aim of this study was to evaluate Ki-67 (MIB-1), CK17 and p16 (INK4a) (p16) markers by immunohistochemical methods in differentiating CIN from benign cervical lesions. METHODS The present study reviewed and re-classified 77 cervical biopsies, originally diagnosed as 31 non-CIN, and 46 CIN, as 54 non-CIN, and 23 CIN based on at least two similar diagnoses. Immunostaining by Ki67, p16 and CK17 markers was performed on all cases and the results were compared with pervious and consensus diagnosis. RESULTS The overall agreement between pervious and consensus diagnosis was 67.5% (Kappa=0.39, P<0.001). The sensitivity and specificity of Ki67 immunostaining were 95.6% and 85.1% respectively, while for p16 the corresponding values were 91.3% and 98.1%. The overall agreement, for both p16 and Ki67, with consensus diagnosis were significant (P<0.001). The sensitivity and specificity of CK17 negative staining in CIN detection were 39.1% and 40.7% respectively. CONCLUSION Ki67 and p16 markers are recommended as complementary tests for differentiating between dysplastic and non-dysplastic lesions. CK17 does not discriminate between immature metaplasia with and without dysplasia.