Conventional cytology, visual tests and evaluation of P16INK4A as a biomarker in cervical intraepithelial neoplasia

OBJECTIVES: (1) To detect cervical intraepithelial neoplasia (CIN) using Papanicolaou test (PAP test), visual tests (visual inspection after the application of acetic acid [VIA], visual inspection after the application of Lugol's iodine [VILI]), colposcopy, and biopsy. (2) To study the biomarker p16(INK4A) expression by immunostaining. MATERIALS AND METHODS: Experimental study was conducted from November 2009 to April 2011. 1500 women were screened for cancer cervix using conventional PAP test, VIA, and VILI. Sensitivity, specificity, positive, and negative predictive values of these tests were calculated individually, sequentially, and in parallel. Women having positive results underwent colposcopy and biopsy if required. p16(INK4A)expression in biopsy samples was studied using immunohistochemistry. RESULTS: All test positive cases (n = 235) underwent colposcopy. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of PAP with atypical squamous cells of undetermined significance (ASCUS) as cut-off was 40%, 99.25%, 35.25%, and 99.39%; VIA was 60%, 93.06%, 8.03%, and 99.56% and VILI was 80%, 86.06%, 5.4%, and 99.76%, respectively. When PAP, VIA, and VILI were used in parallel sensitivity, specificity, PPV, and NPV improved to 100%, 85.18%, 6.38%, and 100%, respectively. Colposcopic abnormalities were detected in 83 and biopsy proven CIN in 15. p16(INK4A) expression was seen in eight of 15 CIN cases. CONCLUSIONS: (1) PAP test and visual techniques are complementary. (2) p16(INK4A)expression was seen in majority of CIN 2 lesions suggesting a higher grade lesion.