HPV L1 and P16 Expression in CIN1 to Predict Future CIN2.

The goal of this study was to use the biomarkers human papillomavirus (HPV) L1 and p16 to develop an algorithm that could triage the individual patient with CIN1 at risk for progression. A total of 82 patients initially diagnosed with CIN1 at Peking University Shenzhen Hospital in China had their initial and follow-up paraffin-embedded tissue blocks immune-stained for HPV L1 capsid protein and p16. For CIN1, any staining of abnormal epithelium was considered positive. All patients were followed until they developed CIN2+ or for ≥3 years. About 38 patients regressed (HPV-, Cytology-), 17 persisted (CIN1), and 27 progressed (≥CIN2+). At initial diagnosis, HPV L1 capsid protein was expressed in 42.7% of the CIN1 cases. There was no difference in L1 expression among the 3 groups. However, p16-positive staining in the progression group was significantly higher than in the regression group (P<0.05). In the regression group, the proportion of HPV L1-/p16- category was significantly higher than that in the progression group. In the progression group, when CIN1 lesions progressed to CIN2+, the L1-positive rate was significantly decreased from 51.9% to 18.5%, the p16+/HPV L1+ rate decreased from the initial (44.4%) to the final diagnosis (14.8%), and the p16+/HPV L1- rate increased from the initial (25.9%) to the final diagnosis (66.7%). P16 expression is a clear risk factor for the progression of CIN1. The p16-/HPV L1- pattern was significantly associated with the regression of CIN1. Moving from CIN1 to CIN2+ over time, p16+/HPV L1+ decreased, and p16+/HPV L1- increased. Unfortunately, our objective of finding a sensitive and specific triage algorithm for the individual patient with CIN1 was not achieved.