Prevalence of cervical intraepithelial neoplasia and invasive carcinoma based on cytological screening in the region of Campinas, São Paulo, Brazil.

This study aimed to estimate and analyze the prevalence of cervical intraepithelial neoplasia (CIN) and invasive cervical carcinoma based on cytological diagnosis. The study included 120,635 women undergoing cytological exams in public health services in the region of Campinas, São Paulo State, Brazil, between September 1998 and March 1999. Prevalence rates per 100,000 women were: 354 for CIN I; 255 for CIN II; 141 for CIN III; and 24 for invasive carcinoma. As age increased, prevalence rates and prevalence ratios decreased for CIN grades I and II and increased for CIN III until the 50-54 age group, decreasing thereafter The prevalence rate of invasive carcinoma increased with age. The prevalence pattern of CIN II was distinct from that of CIN III, but similar to that of CIN I. This would not have been observed if the Bethesda System had been used for cytological diagnosis. Mean age at time of CIN II diagnosis was about 10 years less than for CIN III diagnosis. Therefore, a high-grade lesion diagnosed in a young woman according to the Bethesda System would probably be a CIN II, whereas in an older woman it would probably be a CIN III.