Predicting absolute risk of CIN3 during post-colposcopic follow-up: results from the ASCUS-LSIL Triage Study (ALTS)

Am J Obstet Gynecol. 2006 Aug;195(2):341-8. doi: 10.1016/j.ajog.2006.02.047.


Objective: At present, clinical management of women referred to colposcopy but found to have <CIN2 remains unclear. Using data from the ASCUS-LSIL Triage Study (ALTS) to inform clinical management, we calculated the absolute risk for developing CIN3 within 2 years of referral to an enrollment colposcopy.

Study design: Women included in the analyses: (1) were initially referred to ALTS with a community cytologic interpretation of atypical squamous cell of undetermined significance (ASCUS) or low-grade squamous intraepithelial lesions (LSIL); (2) had a colposcopic evaluation and biopsy, if indicated, resulting in a diagnosis <CIN2; and, therefore (3) were followed without treatment. Results from subsequent human papillomavirus (HPV) testing, liquid-based cytology interpretations, and a second colposcopic evaluation at least 6 months after and within 2 years of the first colposcopic evaluation were used to calculate absolute risks for CIN3.

Results: Women with HPV-negative test results were at low risk for CIN3 regardless of other test results. Among HPV-positive women, increasing absolute risks of CIN3 were observed with increasing cytology severity: 7% (normal), 11% (ASCUS and LSIL), and 45% (HSIL). The highest absolute risk for CIN3 (67%) was observed for HPV-positive women with HSIL and a colposcopic impression of high-grade/cancer on the second colposcopy.

Conclusion: In the ALTS population, after the first colposcopic diagnosis of <CIN2, clear risk stratification for CIN3 outcomes was obtained among women with a subsequent HPV-positive test. Because absolute risk for histologic CIN3 outcomes was high for women with HPV positive tests, HSIL cytology, and a high-grade impression at second colposcopy, it is worth considering whether this combination of findings might warrant immediate excisional therapy in some circumstances.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adult
  • Carcinoma in Situ / diagnosis
  • Carcinoma in Situ / epidemiology*
  • Carcinoma in Situ / pathology
  • Carcinoma in Situ / virology
  • Colposcopy*
  • DNA, Viral / analysis
  • Electrosurgery
  • Female
  • Follow-Up Studies
  • Humans
  • Multicenter Studies as Topic
  • Papillomaviridae / isolation & purification
  • Papillomavirus Infections / epidemiology
  • Practice Guidelines as Topic
  • Predictive Value of Tests
  • Prospective Studies
  • Randomized Controlled Trials as Topic
  • Risk Assessment
  • Sensitivity and Specificity
  • Triage
  • Uterine Cervical Neoplasms / diagnosis
  • Uterine Cervical Neoplasms / epidemiology*
  • Uterine Cervical Neoplasms / pathology
  • Uterine Cervical Neoplasms / virology
  • Vaginal Smears


  • DNA, Viral