Evaluation of P16INK4A as a Biomarker in Cervical Intraepithelial Neoplasia

Introduction: Cervical screening would benefit from a test based on a disease-specific biomarker that identifies high grade lesions, which could also indicate the presence of early precancerous lesions that have a high risk of progression to cancer. One such potential biomarker is p16INK4A. Objective of the study was to study the biomarker p16INK4A expression by immunostaining in cervical intraepithelial neoplasia. Material and method: Experimental study conducted from November 2009 to April 2011. 1500 women were screened for cancer cervix using conventional Pap test, VIA and VILI. Women having positive results underwent colposcopy and biopsy if required. P16INK4A expression in biopsy samples was studied using immunohistochemistry. Results: All test positive cases n= 235, underwent colposcopy. Colposcopic abnormalities were detected in n=83 and biopsy proven cervical intraepithelial neoplasia(CIN) in n=15. P16INK4A expression was seen in eight of 15 CIN cases. The strength of positivity of P16INK4A was higher in CIN 2 and CIN 3 cases as compared to CIN 1. Also, the pattern of staining differed among various grades of CIN. Conclusion: P16INK4A expression was seen in majority of CIN 2 and CIN 3 lesions suggesting a higher grade lesion as compared to CIN 1. The discrimination between the lesions can be made without having to depend on traditional histopathology which gives a static picture of pre-invasive lesions of the cervix. This can help in differentiating high grade lesions from the lower grades, thereby helping in appropriate management