Screening histories of incidence cases of cervical cancer and high grade SIL. A comparison.
OBJECTIVE: To compare the cytologic history of patients with cervical cancer with that of patients with high grade cervical intraepithelial neoplasia (CIN) in order to analyze the causes of screening failure. STUDY DESIGN: In 337 patients treated for high grade CIN and 86 women treated for cancer of the cervix, all cytologic reports from the last five years before diagnosis were reviewed, and slides of normal smears taken within three years of diagnosis were reexamined. RESULTS: Among patients with cancer, 32/86 (37.2%) never had a smear, for 28/86 (32.6%) the time interval between screenings was greater than three years, 12/66 (18.2%) were incorrectly managed after the first abnormal smear, and 7/69 (10.1%) had a normal smear within three years of diagnosis. Conversely, among patients with high grade CIN, 45/337 (13.4%) never had a smear, 60/337 (17.8%) had a time interval between screenings greater than three years, 120/337 (35.6%) were incorrectly managed after the first abnormal smear, and 100/333 (30.0%) had a normal smear within three years of diagnosis. When compared with high grade CIN, cancer of the cervix was associated with absent or insufficient screening (adjusted odds ratio [aOR] = 3.28, 95% confidence interval (95% CI) = 1.86-5.80) but neither with incorrect management of the first abnormal smear (aOR = 1.32, 95% CI = 0.46-3.75) nor with a normal smear within three years of diagnosis (aOR = 0.22, 95% CI = 0.10-0.50). CONCLUSION: Better participation of patients is necessary to improve the efficacy of screening. Conversely, reducing the interval between smears to less than three years would cause a major increase in cost and earlier diagnosis of high grade CIN, but not a significant decrease in the number of cancers.