P16INK4a/ki67 Immunocytochemistry in Improving the Predictive Value for High Grade Cervical Intraepithelial (≥CIN2) Neoplasia in Pap Smear

INTRODUCTION: Cervical cytology has limited sensitivity to detect cervical pre-cancerous lesions. High-risk human papillomavirus (hr-HPV) DNA testing has high sensitivity but its specificity is limited. This study was done to assess the utility of p16(INK4a)/ki-67 dual stained cytology in improving the predictive value for high-grade cervical (CIN2+) lesions. AIM/OBJECTIVE: To assess the significance of P16/Ki-67 immunocytochemistry in improving the predictive value for high-grade cervical intraepithelial (≥CIN 2+) lesions on Pap smear. MATERIAL AND METHODS: This was a prospective diagnostic study that included 93 patients with ASC-US/LSIL/ASC-H and HSIL on thin prep cervical smears and who also underwent hr-HPV DNA test and colposcopy-guided biopsy. Biopsy was the gold standard against which the performance of P16(INK4a)/Ki-67 and hr-HPV results were compared. RESULTS: In women of all ages, sensitivity of (96.8%) hr-HPV test and p16/Ki-67 dual immunocytochemistry (≥1 positive cell) were similar and negative predictive value (NPV) was (97.1% vs. 97.9%) but the latter test showed better specificity (69.4% vs. 53.2%) and positive predictive value (PPV, 61.2% vs. 50.8%) for ≥CIN 2 lesions. A higher cut off of at least 10 positive cells gives a higher specificity and PPV, with slightly decreased sensitivity and NPV. CONCLUSION: Because high-risk HPV test has a high sensitivity and NPV, whereas P16/Ki-67 dual immunocytochemistry (≥10 positive cells) has a high specificity and PPV, the latter can be recommended as an ancillary test in hr-HPV-positive women to reduce the number of women going for colposcopy and biopsies.