Screening histories of women with CIN 2/3 compared with women diagnosed with invasive cervical cancer: a retrospective analysis of the Norwegian Coordinated Cervical Cancer Screening Program.

OBJECTIVE: This study compares the screening history for women with cervical intraepithelial neoplasia (CIN) 2/3 or adenocarcinoma in situ (ACIS) with women with different stages and subtypes of cervical carcinoma.
METHODS: An analysis of the Norwegian Coordinated Cervical Screening Program comparing all cases with a CIN 2/3/ACIS (N=8586) with all ICC (N=777) in the period 2000-2002. All Pap smears since 1992 were used to characterise detection mode and screening history. Multinominal regression models estimated the risk associated with detection mode and adequate Pap smear history.
RESULTS: A wide range of age at diagnosis, from 16 to 92 years of age was observed regardless of the stage of the disease. Fifty five percentage of the women diagnosed with CIN 2/3/ACIS had an adequate screening history. Of women diagnosed with SCC, 45.1% in stage I, and 10.5% in stage IV had an adequate history. The median age of women with CIN 2/3 (34 years) and squamous cervical carcinoma (SCC) stage I (37 years) given an adequate Pap smear history was not significantly different. For women with ACC, the proportion with adequate screening history was roughly 50% for all stages. After adjustment for detection mode and age, the OR for being diagnosed with ICC stage I compared to CIN 2/3 was 1.2 (95% CI: 1.0-1.5), while the OR of being diagnosed with ICC stage II-IV was 3.4 (95% CI: 2.3-4.8).
CONCLUSIONS: Women with CIN 2/3 and ICC stage I were similar with respect to screening histories, i.e. detection mode and age at diagnosis, while women with ICC stage II-IV seldom had an adequate screening history and were diagnosed at a significantly higher age.