CINtec® PLUS dual immunostain: a triage tool for cervical pap smears with atypical squamous cells of undetermined significance and low grade squamous intraepithelial lesion.

ASC and LSIL comprise the majority of abnormal Pap smears. Currently, high-risk human papillomavirus testing is utilized to triage women with ASC for colposcopy; however, no cost effective triage method is available for LSIL. p16 and Ki-67 have each been shown to be good biomarkers for high grade cervical intraepithelial neoplasia (HG CIN).We evaluated the role of the CINtec® PLUS p16/Ki-67 dual immunostain as a marker for underlying (U) or subsequent (S) HG CIN. One hundred and eighty eight cervical SurePath Pap smears with histological and/or cytological follow-up were retrieved from our departmental files. The Pap stained slides were destained and then immunostained utilizing the CINtec® PLUS dual staining reagent kit. Results of the dual stain were correlated with follow-up diagnoses. Sensitivity, specificity, and positive and negative predictive values of CINtec® PLUS for U or S HG CIN were compared with those of HR HPV testing and with p16 and Ki-67 immunostaining alone. The sensitivity of CINtec® PLUS for U or S HG CIN was 91% in the ASC group and 100% in the LSIL group, while the corresponding specificities were 61 and 43%, respectively. The sensitivity and specificity of CINtec® PLUS for U or S HG CIN in both groups combined were 97 and 53%, respectively. CINtec® PLUS was more specific than HR HPV testing and Ki-67 and p16 immunostains alone in detecting an U or S HG CIN. CINtec® PLUS is a helpful adjunct in identifying U or S HG CIN when applied to SurePath Pap smears with ASC or LSIL.