Efficacy of p16 and ProExC immunostaining in the detection of high-grade cervical intraepithelial neoplasia and cervical carcinoma

We compared the efficacy of p16 and ProExC immunostaining in detecting cervical intraepithelial neoplasia (CIN) 2+ in 136 formalin-fixed, paraffinembedded cervical tissue specimens with consensus diagnoses of normal cervix, CIN 1, CIN 2, CIN 3, and carcinoma. Diffuse staining patterns of more than half the thickness of CINs and more than 10% of carcinoma cells were scored as positive. The positivity of p16 and ProExC increased significantly with the severity of cervical lesion (P <.001). For CIN 2+ or CIN 3+, p16 immunostaining was more sensitive (79% for CIN 2+; 90% for CIN 3+) than ProExC immunostaining (67% for CIN 2+; 84% for CIN 3+). ProExC showed higher specificity for CIN 3+ compared with p16. Specimens with p16+/ProExC+ results showed the highest specificity (100% for CIN 2+; 93% for CIN 3+), suggesting that these 2 biomarkers can be used together to distinguish CIN 2/3 from its mimics in cervical biopsy specimens.