Comparison of p16INK4A and Hybrid Capture 2 human papillomavirus testing as adjunctive tests in liquid-based gynecologic SurePath preparations

Abstract

p16(INK4a), cyclin-dependent kinase inhibitor, is functionally inactivated in many tumors, including cervical cancer. We compared p16(INK4A) immunocytochemical staining and Hybrid Capture 2 (HCII) on SurePath specimens using tissue biopsies (as the gold standard). Their utility in a spectrum of atypical and preneoplastic lesions, and their ability to accurately identify underlying lesions of CIN II or greater was assessed using biopsy follow-up data. One-hundred and seventeen residual SurePath samples were collected: 43 atypical squamous cells of undetermined significance (ASCUS), 47 low-grade (LGSIL), and 27 high-grade (HGSIL) squamous intraepithelial lesions. Two slides were prepared from each sample; one stained with the SurePath autocyte stain and one immunostained using the CINtec p16(INK4a) Cytology Kit (Dakocytomation). High-risk HPV testing was performed using the HCII DNA test (Digene, Gaithersburg, MD). Available tissue biopsy follow-up data was retrieved. p16(INK4a) was positive in 32.6% (14/43) ASCUS, 46.8% (22/47) LGSIL, and 48.1% (13/27) HGSIL specimens. HCII DNA test was positive in 41.9% (18/43) ASCUS, 78.7% (37/47) LGSIL, and 96.3% (26/27) HGSIL samples. The sensitivity, specificity, positive (PPV) and negative (NPV) predictive values of p16(INK4a) and HCII were: 58.7% and 89.8%, 58.6% and 34.6%, 69.2% and 72.1%, 47.2% and 64.3%, respectively. In patients with cervical biopsies, the PPV of HCII (92.3%) results for a biopsy with CINII/III was significantly higher than the PPV of p16(INK4a) (52%) (P=0.001). Using liquid-based cytology specimens, HCII is a more sensitive test than p16(INK4a) for detection of abnormal cytology. HCII has a higher PPV than p16(INK4a) for identifying CIN II/III.