Natural history of established low grade cervical intraepithelial (CIN 1) lesions

The aim of the present study was to ascertain the natural history of cervical intraepithelial lesions 1 (CIN 1) and to develop recommendations to optimize follow-up. Patients and Methods: Patients referred for colposcopy from January, 1996 to July, 2005 were reviewed. A prospectively maintained database was quarried for demographic, clinical, and pathologic data. Results: The cohort included 1,001 patients with CIN 1. At 6 months, 330 patients (49%) regressed to normal, 305 (45%) had persistent low grade, while 45 (7%) progressed to high grade lesions. At 12 months, of those with negative pathology at 6 months, 200 (80%) remained negative, 42 (16%) demonstrated low grade and 9 (4%) progressed to high grade lesions. Of those with low grade lesions at 6 months, 131 (50%) regressed, 121 (46%) had persistent low grade, and 10 (4%) progressed to high grade lesions. Conclusion: Our data demonstrates a low rate of progression for CIN 1, suggesting it may be reasonable to prolong the screening interval in women with CIN 1.