title: CIN 2/3 and cervical cancer in an organised screening programme after an unsatisfactory or a normal Pap smear: a seven-year prospective study of the Norwegian population-based screening programme.
abstract: OBJECTIVE
  To estimate the risk of cervical intraepithelial neoplasia (CIN) 2/3 and invasive cervical cancer (ICC) in an organised screening programme after an unsatisfactory or a normal Pap smear.
  
  
  METHODS
  A seven-year prospective cohort study of the Norwegian population-based co-ordinated screening programme based on the actual diagnostic and screening procedures performed. Observations of 526,661 women with a normal index Pap smear and 21,405 women with an unsatisfactory index Pap smear were made during 3.26 million women-years.
  
  
  METHODS
  The risk of being diagnosed with CIN 2/3 or ICC was calculated by logistic regression for the first two years of follow-up. The hazard of being diagnosed with CIN 2/3 or ICC for the women who were not diagnosed during the two first years was estimated by non-parametrical survival regression.
  
  
  RESULTS
  After two years of follow-up, 0.2% of the women were diagnosed with CIN 2/3 and 0.01% with ICC after a normal Pap smear. An unsatisfactory Pap smear indicated a 1.6-4.0 times higher risk of harbouring a CIN 2/3 or ICC compared to women with a normal Pap smear. No increased risk of ICC was found during long-term follow-up for the 70% of the women with an unsatisfactory Pap smear who were returned to ordinary screening. Prior series of low-grade Pap smears followed by a normal Pap were associated with an increased risk of CIN 2/3 and ICC.
  
  
  CONCLUSIONS
  An unsatisfactory Pap smear indicates a risk of harbouring CIN II/III or ICC. Repeated Pap smears are adequate as a follow-up of an unsatisfactory Pap smear. Women with repeated series of equivocal/LSIL Pap smears followed by a normal Pap should be considered at high risk.
authors.affiliation: Screening Department, Cancer Registry of Norway, Institute of Population-based Cancer Research, Montebello, 0310 Oslo, Norway. jan.nygard@kreftregisteret.no
authors.forename: J F
authors.initials: JF
authors.lastname: Nygård
authors.forename: T
authors.initials: T
authors.lastname: Sauer
authors.forename: M
authors.initials: M
authors.lastname: Nygård
authors.forename: G B
authors.initials: GB
authors.lastname: Skare
authors.forename: S Ø
authors.initials: SØ
authors.lastname: Thoresen
mesh_terms: D015331:Cohort Studies; D005260:Female; D006801:Humans; D016015:Logistic Models; D008403:Mass Screening; D009664:Norway; D016017:Odds Ratio; D016016:Proportional Hazards Models; D012042:Registries; D012306:Risk; D013997:Time Factors; D002583:Uterine Cervical Neoplasms / Q000175:diagnosis* / Q000453:epidemiology*; D002578:Uterine Cervical Dysplasia / Q000175:diagnosis* / Q000453:epidemiology*