The clinical meaning of a cervical intraepithelial neoplasia grade 1 biopsy

Objective: To determine whether the diagnosis of cervical intraepithelial neoplasia (CIN) grade 1 increases the risk of CIN 3 above what is observed for human papillomavirus (HPV) infection. Methods: Using data from the atypical squamous cells of undetermined significance (ASCUS) and low-grade squamous intraepithelial lesions (LSIL) triage study, we compared the 2-year cumulative risk of CIN 3 for women with an enrollment diagnosis of CIN 1 (n=594) (median age 23 years) compared with those with negative histology or no biopsy taken at colposcopy ("no CIN 1," n=570) (median age 24 years). Baseline cervical specimens were tested for carcinogenic HPV by a clinical HPV test and HPV genotypes by polymerase chain reaction. Logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs) as a measure of association of enrollment status, including CIN 1 compared with no CIN 1 diagnosis, with 2-year worst outcomes of CIN 3. Results: The two-year risks of CIN 3 were 10.3% (95% CI 7.9-13.0) for women with CIN 1, 7.3% (95% CI 4.6-10.9) for negative histology, and 6.4% (95% CI 3.8-9.9) for women referred to colposcopy and no biopsies were taken (P=.1). The 2-year risks of CIN 3 for women positive for HPV16, HPV18, or other carcinogenic HPV genotypes were 19.1%, 13.9%, and 5.7%, respectively, and did not differ significantly by the baseline cytology interpretation (ASCUS or LSIL). Taking HPV genotypes into account, having a CIN 1 (compared with no CIN 1) was not a risk factor for developing CIN 3 (OR 0.99, 95% CI 0.54-1.8). Conclusion: A CIN 1 diagnosis does not represent a significant risk factor for CIN 3 above the risk attributed to its molecular cause, genotype-specific HPV infection.