p16 Immunohistochemistry in Colposcope-Directed and Random Cervical Biopsies of CIN2 and CIN3.

Overview

OBJECTIVE: The aim of this study was to determine if there is a different p16 expression pattern between colposcope-directed and random (colposcope-undetectable) biopsies of cervical intraepithelial neoplasia (CIN2) and CIN3. METHODS: Cervical biopsies that were positive for CIN2 or CIN3 were selected from a database of samples acquired during a large population-based clinical trial in Guangdong Province in China (Shenzhen Cervical Cancer Screening Study II). Blocks were recut, reread, and then immunostained for p16. Biopsies were categorized as either colposcope-directed or random biopsies. Diffuse staining was considered p16 positive, whereas focal or no staining was considered p16 negative. Differences were determined by the Fisher exact test. RESULTS: Among the patients with CIN3, there were 232 individual biopsies of CIN3. Sixty were randomly collected, and 172 were colposcopy directed. p16 positivity for the colposcope-directed and random biopsies was 97.7% and 91.7%, respectively (p = 0.052). Like the CIN3 biopsies, colposcope-directed and random CIN2 samples expressed p16 similarly (86.8% [46/53] and 82.6% [19/23], p = .73, respectively). CONCLUSIONS: Based on our data, even small colposcope-undetectable biopsies of CIN3 are significant. Random biopsies of CIN2 or CIN3 demonstrate similar p16 positivity as visible lesions and therefore might be expected to have a similar natural history.