Objective: This study aimed to characterize the 24-month risk of cervical intraepithelial neoplasia grade 2 or worse (CIN 2+) and grade 3 or worse (CIN 3+) in women with low-risk cytological finding and CIN 1 on endocervical curettage (ECC).
Materials and Methods: Cervical screening tests and cervical biopsy results from Kaiser Permanente Northern California were reviewed for years 2004 to 2008. Women with index cytological result of atypical squamous cells of undetermined significance or low-grade squamous intraepithelial lesion who underwent excisional procedure within 24 months of CIN 1 diagnosis were grouped by ECC status. A third cohort comprised women with ECC-CIN 1 followed up without excisional procedure. The 24-month cumulative incidence of CIN 2+ and CIN 3+ was calculated for each cohort.
Results: Excisional procedures were performed in 224 women; 54 had ECC-CIN 1 with ectocervical biopsy CIN 1 or less, and 170 had ectocervical CIN 1 with negative ECC finding. The 24-month risk of CIN 2+ was lower in the ECC-CIN 1 cohort compared with the ECC-negative (ectocervical CIN 1) cohort (24.1 vs 44.7%, p = .018) and nonsignificantly lower for CIN 3+ (7.4% vs 14.1%, p = .23). Among 203 women with ECC-CIN 1 followed up without excisional procedure but with follow-up ECC at a median of 21.7 months from index ECC, CIN 2 was found in 21 (10.3%, 95% CI = 6.7%–15.6%), and CIN 3 was found in 3 (1.5%, 95% CI = 0.4%–4.6%).
Conclusions: A diagnosis of CIN 1 on ECC preceded by atypical squamous cells of undetermined significance or low-grade squamous intraepithelial lesion does not increase the risk of CIN 2+ compared with women with ectocervical CIN 1 and negative ECC. The risk of CIN 2+ in women followed up without excisional procedure is sufficiently low that it is reasonable to offer conservative management similar to that for ectocervical CIN 1.