title: Interpretation of p16(INK4a) /Ki-67 dual immunostaining for the triage of human papillomavirus-positive women by experts and nonexperts in cervical cytology.
abstract: BACKGROUND
  The triage of human papillomavirus (HPV)-positive women is needed to avoid overreferral to colposcopy. p16(INK4a) immunostaining is an efficient triage method. p16(INK4a) /Ki-67 dual staining was introduced mainly to increase reproducibility and specificity compared with stand-alone p16(INK4a) staining.
  
  
  METHODS
  Within a pilot project, HPV-positive women were referred to colposcopy if cytology was abnormal or unsatisfactory or HPV testing was still positive after 1 year. For 500 consecutive women, a slide obtained during colposcopy was immunostained for p16(INK4a) /Ki-67 and independently interpreted by 7 readers without previous experience with dual staining. Four of these readers were experts in cervical pathology and 3 were not. Kappa values for multiple raters, sensitivity, and specificity for cervical intraepithelial neoplasia type 2-positive histology were computed. Because women with normal cytology were underrepresented, estimates for all HPV-positive women were obtained as weighted means of cytology-specific estimates.
  
  
  RESULTS
  The overall kappa for HPV-positive women was 0.70 (95% confidence interval [95% CI], 0.60-0.77). Kappa values were not found to be significantly different between expert and nonexpert readers with regard to cervical cytology but were significantly increased (P =. 0066) after consensus discussion. The overall specificity estimate for HPV-positive women was 64.0% (95% CI, 57.4%-70.2%): 66.7% (95% CI, 59.8%-73.0%) for experts and 60.5% (95% CI, 59.8%-73.0%) for nonexperts. Among women with abnormal cytology, the sensitivity was 85.5% (95% CI, 77.9%-90.8%): 85.8% (95% CI, 77.9%-91.2%) for experts and 85.1% (95% CI, 76.6%-90.9%) for nonexperts.
  
  
  CONCLUSIONS
  p16(INK4a) /Ki-67 immunostaining demonstrated good reproducibility and specificity when triaging HPV-positive women. Dual-staining interpretation can be performed, after short training, even by staff who are not experts in cervical cytology. This allows HPV-based screening with triage to be performed in settings in which such expert staff is not available.
authors.affiliation: Center for Cervical Cancer Screening, AO City of Health and Science, Turin, Italy.
authors.forename: Elena
authors.initials: E
authors.lastname: Allia
authors.forename: Guglielmo
authors.initials: G
authors.lastname: Ronco
authors.forename: Anna
authors.initials: A
authors.lastname: Coccia
authors.forename: Patrizia
authors.initials: P
authors.lastname: Luparia
authors.forename: Luigia
authors.initials: L
authors.lastname: Macrì
authors.forename: Corinna
authors.initials: C
authors.lastname: Fiorito
authors.forename: Francesca
authors.initials: F
authors.lastname: Maletta
authors.forename: Cristina
authors.initials: C
authors.lastname: Deambrogio
authors.forename: Sara
authors.initials: S
authors.lastname: Tunesi
authors.forename: Laura
authors.initials: L
authors.lastname: De Marco
authors.forename: Anna
authors.initials: A
authors.lastname: Gillio-Tos
authors.forename: Anna
authors.initials: A
authors.lastname: Sapino
authors.forename: Bruno
authors.initials: B
authors.lastname: Ghiringhello
mesh_terms: D000328:Adult; D002584:Cervix Uteri / Q000378:metabolism / Q000473:pathology; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000378:metabolism*; D003581:Cytodiagnosis; D055088:Early Detection of Cancer; D005104:Expert Testimony; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D019394:Ki-67 Antigen / Q000378:metabolism*; D008875:Middle Aged; D015588:Observer Variation; D030361:Papillomavirus Infections / Q000175:diagnosis*; D010865:Pilot Projects; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014218:Triage / Q000379:methods*; D002583:Uterine Cervical Neoplasms / Q000175:diagnosis*
chemical_list: D019941:Cyclin-Dependent Kinase Inhibitor p16; D019394:Ki-67 Antigen
keywords: cervical cancer; human papillomavirus (HPV)-positive women; interpretation; p16INK4a/Ki-67; readers