Cervical mass screening in Norway--510,000 smears a year.

In 1990 the Norwegian Department of Health and Social Affairs decided to start a national screening program for cervical cancer. All women aged 25 to 70 years are offered cervical screening every 3 years. The mass screening is organized and run by a central unit, comprising the Cancer Registry of Norway and the National Health Screening Service. For the first 3 years, all spontaneous cervical screening in Norway is recorded in a central, computerized register. In addition, a pilot project has been implemented in two counties to evaluate the organizational aspects of the screening program. A total of 509,641 cervical smears were recorded during the first year of registration. The test frequency was highest in the age group 20 to 29 years (28.4%), while relatively few tests were performed on women in the age group 60 to 69 years (6.6%). The majority of smears (88.6%) had normal tissue morphology, whereas 2.9% displayed different cytological abnormalities. Human papillomavirus (HPV) changes and mild (CIN 1) and moderate (CIN 2) dysplasia had the highest smear rate in women under 40 years. Malignant cellular changes had the highest rate in older age groups. The imbalance in the age distribution of smears and the confinement of cytological abnormalities to the youngest and the oldest age groups support the wide target age range of the screening program.