Combined p16INK4a and Human Papillomavirus Testing Improves the Prediction of Cervical Intraepithelial Neoplasia (CIN II-III) in Thai Patients with Low-Grade Cytological Abnormalities

Abstract

Thailand is in the process of developing a national cervical screening program. This study examined p16INK4astaining and HPV prevalence in abnormal cervical samples with atypical squamous cells of undeterminedsignificance (ASCUS) and low-grade squamous intraepithelial lesion (LSIL), to evaluate the efficacy of combinedHPV and p16INK4a detection to predict CIN II-III. Totals of 125 ASCUS and 87 LSIL cases were re-evaluatedby Pap test and cervical cells of ASCUS and LSIL cases were prepared on slides for p16INK4a detection byimmunocytochemistry. HPV genotyping of DNA extracts was performed by GP5+/6+ PCR and reverse line blothybridization. Histopathologic tests were performed to identify cervical lesion. Total of 212 cases were diagnosedto normal (20), ASCUS (112), LSIL (78) and HSIL (2). HPV was detected in ASCUS (49/112, 43.8%), LSIL (60/78,76.9%) and HSIL (2/2, 100%) cases. The majority of HPV positive samples typed for high-risk HPV. 55.7%(107/192) of abnormal cases (ASCUS, LSIL and HSIL) were positive p16INK4a. For the 111 HPV DNA positivecases, 34 of 49 (69.4%) ASCUS cases and 49 of 60 (81.7%) LSIL cases were p16INK4a positive. 140 biopsieswere taken and histological classified: CIN negative (65 cases), CIN I (56 cases) and CIN II-III (19 cases). HPVDNA detection predicted CIN II-III with sensitivity and specificity of 84% and 49%, whereas p16INK4a stainingshowed higher sensitivity (89.5%) and specificity (56.2%). The prediction of CIN II-III was significantly betterby combination of positive HPV DNA and p16INK4a with 93.8% sensitivity and 59.2% specificity. Detectionof HPV DNA combined with p16INK4a in cervical cells can predict CIN II-III and may improve the screeningdiagnosis of Thai women at risk for CIN II-III or cancer.