title: Five-year risk of CIN 3+ to guide the management of women aged 21 to 24 years.
abstract: OBJECTIVE
  Current US national guidelines recommend beginning screening at age 21 using Pap tests only, with cotesting starting at age 30. To inform the management of Pap test abnormalities among women aged 21 to 24 years, who have extremely low cancer risks, we compared risks of CIN 3+ among women aged 21 to 24 versus 25 to 29 years or 30 to 64 years.
  
  
  METHODS
  We estimated 5-year risks of CIN 3+ given different Pap test results, with human papillomavirus (HPV) triage of atypical squamous cells of undetermined significance (ASC-US), among 133,947 women aged 21 to 24 years, compared with 135,382 women aged 25 to 29 years and 965,360 women aged 30 to 64 years, between 2003 and 2010 at Kaiser Permanente Northern California.
  
  
  RESULTS
  There were 3 cancers diagnosed during follow-up in women aged 21 to 24 years. After high-grade Pap results (0.6% of Pap results), the 5-year CIN 3+ risks among women aged 21 to 24 years were comparable to those aged 25 to 29 and 30 to 64 years (atypical glandular cells, 6.9% vs 14% vs 8.5%, p = .8; atypical squamous cells cannot rule out high-grade squamous intraepithelial lesion, 16% vs 24% vs 18%, p = .8; high-grade squamous intraepithelial lesion, 28% vs 28% vs 47%, p = .4). After low-grade squamous intraepithelial lesion, the 5-year CIN 3+ risk was lower among women aged 21 to 24 years (3.0%) than that among women aged 25 to 29 years (5.0%, p = .01) or aged 30 to 64 years (5.2%, p = .0002). Although the 5-year CIN 3+ risk after HPV-negative/ASC-US was similar across all 3 groups (0.57% vs 0.59% vs 0.43%, p = 1), risk after HPV-positive/ASC-US was lower among women aged 21 to 24 years (4.4%) than that among women aged 25 to 29 years (7.1%, p < .0001) or 30 to 64 years (6.8%, p < .0001).
  
  
  CONCLUSIONS
  Women aged 21 to 24 years had almost zero cancer risk, and positive Pap test results predicted low CIN 3+ risk except for the 0.6% of women with high-grade Pap results. The generally low risk supports conservative management of women aged 21 to 24 years.
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health/DHHS, Bethesda, MD 20892, USA. katkih@mail.nih.gov
authors.forename: Hormuzd A
authors.initials: HA
authors.lastname: Katki
authors.forename: Mark
authors.initials: M
authors.lastname: Schiffman
authors.forename: Philip E
authors.initials: PE
authors.lastname: Castle
authors.forename: Barbara
authors.initials: B
authors.lastname: Fetterman
authors.forename: Nancy E
authors.initials: NE
authors.lastname: Poitras
authors.forename: Thomas
authors.initials: T
authors.lastname: Lorey
authors.forename: Li C
authors.initials: LC
authors.lastname: Cheung
authors.forename: Tina
authors.initials: T
authors.lastname: Raine-Bennett
authors.forename: Julia C
authors.initials: JC
authors.lastname: Gage
authors.forename: Walter K
authors.initials: WK
authors.lastname: Kinney
mesh_terms: D000328:Adult; D002140:California / Q000453:epidemiology; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008403:Mass Screening / Q000379:methods; D030361:Papillomavirus Infections / Q000175:diagnosis*; D018570:Risk Assessment; D002583:Uterine Cervical Neoplasms / Q000175:diagnosis* / Q000453:epidemiology*; D014626:Vaginal Smears / Q000379:methods*; D014773:Virology / Q000379:methods*; D055815:Young Adult; D002578:Uterine Cervical Dysplasia / Q000175:diagnosis* / Q000453:epidemiology*