Trends in the prevalence of cervical intraepithelial neoplasia grade 3 in the district of Florence, Italy.

Abstract

The objective of this study was to investigate the detection rate of cervical intraepithelial neoplasia grade III (CIN 3) in previously unscreened women, in order to reveal trends over time in the prevalence of CIN 3 in the District of Florence, where a population-based screening for cervical cancer has been going on since 1973. We considered the women, recorded in the computerized archives of CSPO, who had had no pap test for at least 10 years. Trends of CIN 3 (histologically proven) were analyzed within age groups; the effect of age, cohort and period were considered by means of a Poisson regression model. A total of 648 cases of histologically proven CIN 3 were detected in the study period. The detection rates of CIN 3 increased steadly within age groups over birth cohort and calendar period simultaneously. The Poisson regression analysis showed that only the model with age + time trend was statistically significant. Although several biases should be taken into account, the analysis seemed to indicate a real increase in CIN 3 prevalence. An increase in frequency of precancerous lesions for cervical cancer in more recent birth cohorts supports the need to keep screening coverage and efficiency as high as possible.