NATURAL-HISTORY OF CERVICAL SQUAMOUS INTRAEPITHELIAL LESIONS - A METAANALYSIS

Objective: To define the strengths and weaknesses of existing research on the natural history of cervical squamous intraepithelial lesions ( SIL) and to estimate rates of progression and regression without treat ment. Data Sources: Studies of women whose cervical smears showed squa mous atypia or worse and who were observed for a minimum of 6 months w ere identified by a search of MEDLINE from 1966 to 1996, Current Conte nts, the Federal Research in Progress database, and references of revi ew articles and identified studies, and by experts in the field. Metho ds of Study Selection: Fifteen of 81 studies were eligible for data ex traction. To be eligible, studies had to report a minimum of 6 months' follow-up without treatment; relate entry cytologic findings to outco mes; and report entry cytologic findings so that the study population could be stratified into categories oi: atypical cells of undetermined significance (ASCUS), low-grade SIL, or high-grade SIL. Studies publi shed before 1970 were excluded. Tabulation, Integration, and Results: Eligible studies, representing 27,929 patients, were stratified accord ing to entry cytologic findings. The following rates of progression to high-grade SIL at 24 months were found: ASCUS, 7.13% (95% confidence interval [CI] 0.8%, 13.5%); low-grade SIL, 20.81% (6.08%, 35.55%); and high-grade SIL, 23.37% (12.82%, 32.92%). The following rates of invas ive cancer at 24 months were found: ASCUS, 0.25% (0%, 2.25%); low-grad e SIL, 0.15% (0%, 0.71%); and high-grade SIL, 1.44% (0%, 3.95%). The f ollowing rates of regression to normal were found: ASCUS, 68.19% (57.5 1%, 78.86%); low-grade SIL, 47.39% (35.92%, 58.86%); and high-grade SI L, 35.03% (16.57%, 53.49%). Study heterogeneity was not explained by r egression analysis of study level variables. Conclusion: Our findings for borderline and low-grade abnormal cervical cytologic results sugge st a relatively low risk of invasive cervical cancer with observation up to 24 months and support the clinical policy of early colposcopy fo r high-grade lesions. (Obstet Gynecol 1998;92:727-35. (C) 1998 by The American College of Obstetricians and Gynecologists.).