Risk of CIN2 in Women With a Pap Test Without Endocervical Cells vs. Those With a Negative Pap Test With Endocervical Cells: A Cohort Study with 4.5 Years of Follow-up

To measure the risk of cervical intraepithelial neoplasia grade 2 or higher (CIN2+) in the 4.5 years following a negative Pap smear with adequate endocervical cells (ECC) (+) or absent/scarce ECC (-). A prospective, nonconcurrent study of the archives of 11 Italian population-based screening programs was conducted. Only 25-50-year-old women with a first negative Pap test were included. Women were classified as ECC+ or ECC- and followed for 4.5 years. The endpoint was the occurrence of a CIN2+ histologic diagnosis. Eligible subjects with negative Pap tests ECC+ and ECC- numbered 469,694 and 20,596, respectively. At least 1 subsequent test was available during follow-up for 335,763 and 11,972 subjects, and 691 and 13 CIN2+ lesions were observed, respectively. The risk of CIN2+ was 2.06 and 1.09 per 1,000 women over 4.5 years, and age-adjusted relative risk associated with ECC--was 0.55 (95% CI 0.28-1.06). Women with a negative Pap ECC--have a lower risk of CIN2+ than women with a negative Pap ECC+ and should repeat screening with frequency (3-5 years in Europe), independent of age.