Natural History of Low-Grade Squamous Intraepithelial Lesion

Abstract

The authors followed 158 women with a cervical smear showing low-grade squamous intraepithelial lesion (LGSIL) who had been diagnosed with cervical intraepithelial neoplasia (CIN) 1 by a colposcopically directed biopsy. The participants were not treated but were followed closely with colposcopic examination every 3 months and periodic Pap smears and human papillomavirus (HPV) testing. Other than the initial biopsy at study entry, cervical biopsies were done only when colposcopic or cytologic evidence of progression was observed. Follow-up was discontinued for women who developed CIN 2 or CIN 3, and they were treated appropriately. Persistence or regression was defined by colposcopy. The average length of follow-up was 24 months (range, 12-60). All patients had at least four follow-up visits. Fifty-four women (34%) had regression of CIN 1. 87 (55%) had persistent CIN 1, and 17 (11%) progressed to CIN 2 (15 patients) or CIN 3 (2 patients). The fastest time to development of high-grade squamous intraepithelial lesion (HGSIL) was 12 months. This patient was positive for HPV type 16. Of the 54 patients with untreated CIN 1 whose colposcopic lesion regressed, 33 (61%) regressed to normal cytology, 17 to atypical squamous cells of undetermined significance (ASCUS), and four continued to have LGSIL cytology. Thirty-one (36%) of the 87 women in the persistence group eventually had a normal Pap smear at their last visit; 26 (30%) regressed to ASCUS and 30 (34%) remained LGSIL. A similar distribution of cytology was seen in the group with biopsy-proven progression. In these 17 patients, 5 women (29%) had normal Pap tests, 7 (41%) had ASCUS, and 5 (30%) continued to have LGSIL. A significant trend for an increasing rate of abnormal cytology with persistent or progressive lesions was seen (P = 001 compared with the group who regressed). Among the 73 women in whom HPV testing was performed, 16 of 19 patients in the regression group were negative for HPV (84%). Twenty-six of the 37 members of the persistence group were negative for HPV (70%), and 11 were positive (30%). In the 17 patients in the progression group, only 6 (35%) were negative for HPV and 11 (65%) were positive for HPV (P = .007).