Validation of a novel immunocytochemical assay for topoisomerase II-alpha and minichromosome maintenance protein 2 expression in cervical cytology.
BACKGROUND
Cervical cytopathology has limited specificity for the detection of underlying clinically significant lesions in cases with low-grade cytologic abnormalities. The current study evaluated the performance of a novel immunocytochemical test (ProEx C) for topoisomerase II alpha (TOP2A) and minichromosome maintenance protein 2 (MCM2) in normal versus high-grade squamous intraepithelial lesion (HSIL) and positive control (SiHa) pooled cytology preparations and in a pilot series of prospectively collected patient specimens.


METHODS
TOP2a and MCM2 were detected as markers of aberrant S-phase induction in SurePath cervical cytology specimens by an indirect polymer-based immunoperoxidase method (ProEx C, TriPath Oncology, Burlington, NC). Slides were scored based on specimen adequacy, the presence of nuclear stain in epithelial cells, and the association of nuclear staining with cytologic atypia (>/=atypical squamous cell of undetermined significance [ASC-US] or atypical glandular cells [AGC]).


RESULTS
Intense nuclear staining was detected in cytologically abnormal cells but not in most normal squamous and glandular cells. Slides were scored positive in pooled samples in 1 of 40 (2.5%) cases that were negative for intraepithelial neoplasia or malignancy (NIL), in 40 of 40 (100%) SiHa-spiked NIL, and in 40 of 40 (100%) HSILs. There was 100% concordance in test classification of 20 slides between 2 pathologists. Subsequent evaluation of prospectively collected patient specimens was positive for ProEx C in none of 10 NIL (0%), 2 of 10 ASC-US (20%), 5 of 10 low-grade SIL (LSIL) (50%), and in 10 of 10 (100%) HSILs.


CONCLUSIONS
The ProEx C test showed almost no variability with regard to scoring and staining reproducibility and was consistently positive in HSIL. Further studies are indicated to evaluate the potential role of ProEx C as a diagnostic adjunct for the triage of ASC-US/LSIL.
Shroyer
Kenneth R
KR
Department of Pathology, University of Colorado at Denver and Health Sciences Center, Aurora, Colorado, USA. Ken.Shroyer@uchsc.edu
Homer
Petra
P
Heinz
David
D
Singh
Meenakshi
M
D000465:Algorithms; D000951:Antigens, Neoplasm / Q000096:biosynthesis*; D014408:Biomarkers, Tumor / Q000032:analysis; D018797:Cell Cycle Proteins / Q000096:biosynthesis*; D004250:DNA Topoisomerases, Type II / Q000096:biosynthesis*; D004268:DNA-Binding Proteins / Q000096:biosynthesis*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods*; D064111:Minichromosome Maintenance Complex Component 2; D009687:Nuclear Proteins / Q000096:biosynthesis*; D010865:Pilot Projects; D000075223:Poly-ADP-Ribose Binding Proteins; D015203:Reproducibility of Results; 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; D014408:Biomarkers, Tumor; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D000075223:Poly-ADP-Ribose Binding Proteins; C084859:MCM2 protein, human; D064111:Minichromosome Maintenance Complex Component 2; D004250:DNA Topoisomerases, Type II; C000618811:TOP2A protein, human