p16INK4A expression in cervical intraepithelial neoplasia and cervical cancer

Introduction: Cervical cancer is the third most common cancer among women and is more common in developing countries such as India, due to lack of good screening tests. The efficacy of the Pap smear is hampered by high inter-observer variability and high false positive and false negative rates. Liquid based cytology has not been shown to improve sensitivity or specificity when compared to Pap smear. Histological assessment which is considered the gold standard is also hampered by intraand inter-observer variability. This study was undertaken to assess the p16ink4a expression in cervical intraepithelial neoplasia and invasive squamous cell carcinoma of the cervix and its role in a developing country. Materials and Methods: This was a retrospective study of a total of 80 cases with 16 cases each of chronic nonspecific cervicitis, cervical intraepithelial lesion CIN1, CIN2, CIN3, and invasive squamous cell carcinoma, on which immunohistochemistry was performed with primary mouse monoclonal antibody (Immunogen clone G175, SOTYPE IgG). Results: The p16ink4a expression score associated well with the degree of cervical neoplasia from chronic non-specific cervicitis to the invasive cervical cancer group. The percentage of tumour cells showing progressive increase in the positive staining; Chronic non-specific cervicitis 25% (n=4/16) positivity, CIN1 62.6% (n=10/16), CIN2 75% (n=12/16), CIN3 81.2% (n=13/16) and there was 100% positivity of p16ink4a staining in squamous cell carcinoma. Conclusion: Our study confirmed the usefulness of p16ink4a and findings from this study reiterate its importance for a low resource setting also.