Potential diagnostic value of P16 expression in premalignant and malignant cervical lesions

The goal of this study was to evaluate the results of the expression of p16INK4a in normal uterine cervical epithelium, low-grade cervical intraepithelial neoplasia, (CIN) high-grade CIN, squamous cell carcinoma (SCC), and adenocarcinoma of the cervix, in order to help draw a distinction between low risk and high risk patients with cervical lesions. P16INK4a expression was evaluated by immunohistochemistry in 78 paraffin-embedded tissue samples including 39 normal cervical tissues, 11 low-grade CINs, 11 high-grade CINs, 22 cervical SCCs and 8 cervical adenocarcinomas. Two parameters in immunohistochemical p16 expression were evaluated: percentage of p16-positive cells, and reaction intensity. The p16INK4a expression rate was 81.8% in low-grade CINs, 91% in high-grade CINs, 90% in SCCs and 75% in cervical adenocarcinomas. 10% of normal cervical samples expressed p16. Moreover, there is a significant relationship between the histological diagnoses and percentage of positive cells and reaction intensity of p16 (p < 0.005). The intensity of the reaction is the best parameter to evaluate the positivity of p16. Over-expression of the p16INK4a is typical for dysplastic and neoplastic epithelia of the uterine cervix. However, p16INK4a-negative CINs and carcinomas do exist. Although negative p16INK4a expression does not definitely exclude the patient with cervical lesion from the high-risk group, immunohistochemical study for p16INK4a may be used as a supplementary test for an early diagnosis of cervical cancers.