ObjectiveTo assess the risk of residual and recurrent disease after carbon dioxide laser conization treatment for high-grade lesions of the cervicx uteri, and thus to refine intervals for follow-up.MethodsThe study population comprised all women treated for cervical intraepithelial neoplasia grade II-III over a 10-year period (1983–1992). All women who resided within the county for the entire follow-up period were followed for residual or recurrent disease, verified histologically until the closure date of january 31, 1996. The cumulative incidence of recurrent disease was assessed by survival analyses, and logistic regression was used to predict clinical features at initial treatment that were associated with the risk of residual or recurrent disease.ResultsOnly 10 of 1081 women (1.8%) were lost to follow-up. Residual disease was diagnosed in 20 (1.9%) study participants. The cumulative incidence ofrecurrent disease was extremely low, increasing nearly linearly with an annual incidence of three per 1000 woman-years observed. Involved resection margins were associated significantly with both residual disease (crude odds ratio [OR] 18.1; 95% cinfidence iterval [CI] 5.2, 64.0) and recurrent disease (adjusted OR 3.0; 95% CI 1.2, 7.5) when compared with disease-free resection margins as reference.ConclusionWe recommend a differential follow-up interval depending upon the histologic evaluation of cone margins. If there is no residual disease, women who have free resection margins should return at a 3-year interval for follow-up. Women who have disease extended to the cone margins are recommended Papanicolaou smears at annual intervals through the fourth postoperative year before returning at a 3-year interval as practiced in the general screening program.