Usefulness of P16 and KI67 Immunostaining in Cervical Smear Cytology in Guatemalan Women: A Cross-Sectional Study

Abstract

Background: Conventional cytology is an economic method for screening abnormalities in cervical smears, but with implications in false positive and false negative as compared to better detection of transformed cells with the Dual staining P16/KI67 proteins in cervical smears, therefore, we evaluate the validity and reproducibility of cytology with double staining of P16 and KI67 as compared to conventional cytology in cervical smears. Patients and methods: Participants were 210 Guatemalan women with abnormalities in conventional cytology (ASCUS, AGUS, ASCH, LSIL, HSIL, and cervical cancer) that consulted from 2013-2014 to the colposcopy Unit of Liga Nacional Contra El Cáncer e Instituto de Cancerología y Hospital Dr. Bernardo del Valle S. in Guatemala, from whom smear cytology was processed with P16 and KI67 immunostaining, and histological sections with P16 immunostaining as gold standard. They were evaluated by three blinded pathologists and one independent cytotechnologist. Results: The sensitivity and specificity of Dual staining P16/ KI67 for detecting abnormalities in cervical smears was 78.95%, 95% confidence interval (CI) 71.03-86.87 and 94.74%, 95%CI 89.06-100 respectively, as compare to conventional cytology in which it was 78.64% and 75.85%, respectively; positive predictive value (PPV) and negative predictive value (NPV) of Dual staining P16/KI67 were 95.74%, 95%CI 91.13-100.0 and 75%, 95%CI 65.82-84.18, as compare to conventional cytology in which it was 79.41% and 75% respectively. In women older than 30 years the sensitivity and PPV of Dual staining P16/KI67 was 78.43% and 95.24%, as compare in women less than 30 years in which it was 41.67% and 83.33% respectively. Interobserver agreement weighted Kappa indices for cervical smear cytology with double staining ranged between 0.66 to 0.83. Conclusion: Dual staining P16/KI67 in women older than 30 years showed better sensitivity and PPV values, suggesting greater utility in this age group, although the sensitivity was like conventional cytology, but with greater specificity and PPV.