Detection of cervical high-grade squamous intraepithelial lesions from cytologic samples using a novel immunocytochemical assay (ProEx C).
BACKGROUND
Routine liquid-based cytology (LBC) provides excellent sensitivity for the detection of cervical high-grade squamous intraepithelial lesion (HSIL); however, its specificity is low. Consequently, many women who have atypical squamous cells of undetermined significance (ASC-US) or low-grade squamous intraepithelial lesion (LSIL) cytology undergo unnecessary colposcopy. The authors hypothesized that a novel immunocytochemical assay (ProEx C) that can be performed on LBC slides had a significantly higher positive predictive value (PPV) for biopsy-proven HSIL compared with routine LBC.


METHODS
The ProEx C immunocytochemical assay utilizes a cocktail of monoclonal antibodies directed against proteins associated with aberrant S-phase cell cycle induction (topoisomerase IIA, minichromosome maintenance protein 2). The ProEx C reagents were validated in the authors' laboratory for staining and scoring reproducibility, open-vial stability, and accuracy before a retrospective analysis using these reagents was performed on 317 residual cytology samples. Sensitivity, specificity, PPV, and negative predictive value (NPV) for the detection of biopsy-proven HSIL were determined.


RESULTS
The ProEx C assay was validated successfully in the authors' cytology laboratory. Using biopsy-proven HSIL as an endpoint, the ProEx C assay yielded a sensitivity of 85.3%, specificity of 71.7%, PPV of 44.6%, and NPV of 94.8%. Compared with the routine LBC results in the same cohort, the ProEx C sensitivity for biopsy-proven HSIL was 70.6% greater than HSIL+ cytology (50% vs. 85.3%). ProEx C also showed a 114% increase in PPV relative to ASC-US cytology (21.1% vs. 44.6%).


CONCLUSIONS
The ProEx C immunocytochemical assay can be integrated into a clinical cytology laboratory and may increase the PPV of LBC for biopsy-proven HSIL.
Kelly
Deidra
D
Department of Pathology, The Johns Hopkins Medical Institutions, Baltimore, MD 21287-6940, USA.
Kincaid
Erik
E
Fansler
Zoya
Z
Rosenthal
Dorothy L
DL
Clark
Douglas P
DP
D000465:Algorithms; D000951:Antigens, Neoplasm / Q000378:metabolism*; D001681:Biological Assay; D018797:Cell Cycle Proteins / Q000378:metabolism*; D004250:DNA Topoisomerases, Type II / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005260:Female; D006801:Humans; D064111:Minichromosome Maintenance Complex Component 2; D018307:Neoplasms, Squamous Cell / Q000175:diagnosis* / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism*; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D002583:Uterine Cervical Neoplasms / Q000175:diagnosis* / Q000378:metabolism; D014626:Vaginal Smears; D002578:Uterine Cervical Dysplasia / Q000175:diagnosis* / Q000378:metabolism
D000951:Antigens, Neoplasm; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; C084859:MCM2 protein, human; D064111:Minichromosome Maintenance Complex Component 2; D004250:DNA Topoisomerases, Type II