title: Interobserver reproducibility and accuracy of p16/Ki-67 dual-stain cytology in cervical cancer screening.
abstract: BACKGROUND
  Dual-stain cytology for p16 and Ki-67 has been proposed as a biomarker in cervical cancer screening. The authors evaluated the reproducibility and accuracy of dual-stain cytology among 10 newly trained evaluators.
  
  
  METHODS
  In total, 480 p16/Ki-67-stained slides from human papillomavirus-positive women were evaluated in masked fashion by 10 evaluators. None of the evaluators had previous experience with p16 or p16/Ki-67 cytology. All participants underwent p16/Ki-67 training and subsequent proficiency testing. Reproducibility of dual-stain cytology was measured using the percentage agreement, individual and aggregate κ values, as well as McNemar statistics. Clinical performance for the detection of cervical intraepithelial neoplasia grade 2 or greater (CIN2+) was evaluated for each individual evaluator and for all evaluators combined compared with the reference evaluation by a cytotechnologist who had extensive experience with dual-stain cytology.
  
  
  RESULTS
  The percentage agreement of individual evaluators with the reference evaluation ranged from 83% to 91%, and the κ values ranged from 0.65 to 0.81. The combined κ value was 0.71 for all evaluators and 0.73 for cytotechnologists. The average sensitivity and specificity for the detection of CIN2+ among novice evaluators was 82% and 64%, respectively; whereas the reference evaluation had 84% sensitivity and 63% specificity, respectively. Agreement on dual-stain positivity increased with greater numbers of p16/Ki-67-positive cells on the slides.
  
  
  CONCLUSIONS
  Good to excellent reproducibility of p16/Ki-67 dual-stain cytology was observed with almost identical clinical performance of novice evaluators compared with reference evaluations. The current findings suggest that p16/Ki-67 dual-stain evaluation can be implemented in routine cytology practice with limited training.
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, Maryland.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Wentzensen
authors.forename: Barbara
authors.initials: B
authors.lastname: Fetterman
authors.forename: Diane
authors.initials: D
authors.lastname: Tokugawa
authors.forename: Mark
authors.initials: M
authors.lastname: Schiffman
authors.forename: Philip E
authors.initials: PE
authors.lastname: Castle
authors.forename: Shannon N
authors.initials: SN
authors.lastname: Wood
authors.forename: Eric
authors.initials: E
authors.lastname: Stiemerling
authors.forename: Nancy
authors.initials: N
authors.lastname: Poitras
authors.forename: Thomas
authors.initials: T
authors.lastname: Lorey
authors.forename: Walter
authors.initials: W
authors.lastname: Kinney
mesh_terms: D000328:Adult; D014408:Biomarkers, Tumor / Q000378:metabolism; D002294:Carcinoma, Squamous Cell / Q000175:diagnosis* / Q000378:metabolism / Q000821:virology; D003127:Colposcopy; D019941:Cyclin-Dependent Kinase Inhibitor p16; D003581:Cytodiagnosis; D055088:Early Detection of Cancer; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D019394:Ki-67 Antigen / Q000378:metabolism*; D060787:Neoplasm Grading; D009363:Neoplasm Proteins / Q000378:metabolism*; D015588:Observer Variation; D027383:Papillomaviridae / Q000302:isolation & purification; D030361:Papillomavirus Infections / Q000175:diagnosis / Q000378:metabolism / Q000821:virology; D011379:Prognosis; D012015:Reference Standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013194:Staining and Labeling; D002583:Uterine Cervical Neoplasms / Q000175:diagnosis* / Q000378:metabolism / Q000821:virology; D014626:Vaginal Smears; D002578:Uterine Cervical Dysplasia / Q000175:diagnosis* / Q000378:metabolism / Q000821:virology
chemical_list: D014408:Biomarkers, Tumor; C000614131:CDKN2A protein, human; D019941:Cyclin-Dependent Kinase Inhibitor p16; D019394:Ki-67 Antigen; D009363:Neoplasm Proteins
keywords: Ki-67; Papanicolaou test; cervical cancer screening; cytology; human papillomavirus; p16; reproducibility