Management of HPV-Related Cervical Disease: Role of p16 INK4a Immunochemistry. Review of the Literature

This systematic review of 43 studies aims to evaluate the absolute and relative sensitivity and specificity of p16 INK4a with regard to uterine cervix lesions, describing innovations and techniques for the detection of high-grade cervical dysplasia and allowing correct treatment. Studies were identified in the PubMed database up to March 2015. The keywords hrHPV, p16 INK4a gene, and uterine cervical disease (MeSH terms) were used. Only English-language articles were included. We considered retrospective and prospective studies that assessed p16 INK4a or p16 INK4a /Ki67 staining, with or without HPV-DNA testing (HC2/PCR) as a comparator test, in cytological/histological specimens for which the diagnosis of ASCUS, LSIL or HSIL was verified with a reference standard. The primary outcome for cervical lesions was evaluation of the absolute p16 INK4a immunoreactivity; the secondary outcome was evaluation of the relative p16 INK4a immunoreactivity versus HPV testing in those studies where comparator tests were available. p16 INK4a was more specific than HPV-DNA test (median values of 56.1% vs. 52.25% in CIN grade ≥2 lesions; 82.5% vs. 53% in negative and CIN grade ≥1 lesions). The main limitation of this study is linked to both qualitative and quantitative p16 INK4a levels of expression, while the second limitation is the lack of standardized scales. p16 INK4a and HPV-DNA used together increased the sensitivity and negative predictive value for CIN detection. p16 INK4a can be considered a biomarker of CIN2 or CIN3, indicating a high risk of relapse or evolution to invasive carcinoma. Also p16 INK4a -negative CIN should be considered and further research should be performed.