Objective: The purpose of this study was to determine the risk of cumulative cervical intraepithelial neoplasia (CIN) grade 2 or 3 according to initial colposcopy and directed biopsy results among women with low-grade squamous intraepithelial lesions (LSIL) or human papillomavirus (HPV) DNA positive atypical squamous cells of undetermined significance (ASCUS).
Study design: A 2-year follow-up of 897 cases of LSIL and 1193 cases of HPV DNA positive ASCUS from the ASCUS/LSIL Triage Study was used to simulate American Society for Colposcopy and Cervical Pathology Consensus Conference recommendations. Women with CIN grade 1 or less were followed up for 2 years by semiannual cytologic examination, with universal exit colposcopy. The clinical end point was a cumulative clinical center histologic diagnosis of CIN grade 2 or 3.
Results: The cumulative risk of CIN grade 2 or 3 was equivalent for LSIL (27.6%) and HPV positive ASCUS (26.7%). After excluding the women with a diagnosis of CIN grade 2 or 3 at initial colposcopy and directed biopsy (17.9%), the remaining women were at nearly identical risk for subsequent CIN grade 2 or 3 regardless of initial colposcopy result (completely negative colposcopy-11.3%; negative colposcopically directed biopsy-11.7%; and CIN grade 1 biopsy-13.0%).
Conclusion: LSIL and HPV positive ASCUS are clinically equivalent. Initial colposcopic detection of obviously prevalent CIN grade 2 or 3 reduces risk. However, for the remaining women who have CIN grade 1 or less on colposcopy and directed biopsy, the risk for subsequent CIN grade 2 or 3 (whether missed, prevalent, or truly incident) is approximately 12% over 2 years. This risk does not vary meaningfully by initial distinction of histologic CIN grade 1 from negative colposcopy and biopsy.