The cervical cancer screening programme in Norway, 1992-2000: changes in Pap smear coverage and incidence of cervical cancer.

OBJECTIVES: Changes in the incidence of cervical cancer were studied to assess the impact of the Norwegian coordinated cervical cancer screening programme introduced in 1995. Attention was given as to whether recommendation letters sent to women without a screen in the previous 3 years could be an alternative to a conventional screening programme that invites women irrespectively of their spontaneous screening.
SETTING: A population based, nationwide, screening programme in which women of 25 to 69 are recommended to have a conventional Pap smear every 3 years.
METHODS: The impact of the screening programme was assessed indirectly by comparing trends in invasive cervical cancer, changes in coverage, and changes in interval between Pap smears in the 3 year period (1992-4) before screening with the two first screening rounds (1995-7 and 1998-2000). All Pap smears taken from women of all ages were included, a total of 4 744 967 Pap smears from more than 1.4 million women. Further, the impact was assessed directly by logistic regression by comparing the screening results of women recruited for the programme with women who had regularly had Pap smears.
RESULTS: In the last 2 years studied, the incidence of invasive cancer was 22% lower than in the period before the programme. The proportion of women who had a Pap smear was higher after the implementation of the coordinated screening programme. The number of smears taken was less as the interval after a normal smear was greater. The newly recruited women had a threefold risk of having a high grade precursor and a 20-fold higher risk of cancer than the women who had had regular smears.
CONCLUSIONS: The coordinated screening programme provides a low cost way of increasing the coverage of the female population, and consequently has reduced the rate of invasive cervical cancer.