Natural history of low-grade squamous intraepithelial lesion

Objective. To determine guidelines for management of CIN1 by evaluating its natural history. Methods. One hundred fifty-eight patients were diagnosed with CIN1 had colposcopy follow-up with or without cytology every three months. Results. Colposcopically directed biopsy confirmed progression to CIN2 or CIN3 in 17 of 158 (10.7%) patients, persistence of CIN1 in 87 (55%) patients, regression to normal in 54 (34.2%) patients during the 5-year follow-up period. The percentage of abnormal Pap tests were 39%, 64%, and 71% in the regression, persistent, and progression groups, respectively. The percentage of HPV-positive tests were 16%, 29%, 65% in regression, persistent, and progression groups, respectively. Conclusions. Of the patients who were diagnosed with CIN1 and monitored by colposcopy for 60 months, 34% had disease regression, 55% had persistent disease, and 11% had progressive disease. HPV DNA testing is more informative than the Pap test in the prediction of disease progression.