Trends in cervical intra-epithelial neoplasia in Iceland through 1995: evaluation of targeted age groups and...

Targeted age groups and screening intervals are dependent on the age-specific prevalence of the preclinical disease and the length of the detectable pre-clinical phase. This study evaluates the UICC and EC recommendations regarding targeted age group and screening intervals based on the Icelandic screening experience.

The trends for cytologic preinvasive lesions were analyzed at first visit during the period 1966-1995, at second and later visits after a normal test(s) taken after 1985, and finally at any visit in 1991-1995. The frequency of histologic lesions was calculated for the birth cohort from the age of 60 and among women referred for colposcopic examination in 1994.

The prevalence of preinvasive disease has increased significantly since 1980, and the rate of moderate to high-grade cytologic and histologic lesions begins increasing as early as 20 years of age. The rate of these lesions starts to accumulate at 24 to 36 months after a normal smear, but the rate decreases with the number of negative smears taken. Among correctly screened women the rate of histologically verified moderate to high-grade lesions and invasive disease is practically non-existent after the age of 60, while among the younger women cases with microinvasive disease start to appear within 2 to 3 years after a normal smear.

Screening should start soon after age 20 with a screening interval of 2 to 3 years. The screening interval can probably be extended to 4 years at the age of 50 and stop at the age of 60 to 64 among regularly screened women.