Regional trends in incidence of cervical cancer in Denmark in relation to local smear-taking activity.

In this study the regional trends in the incidence of cervical cancer in Denmark from 1943 to 1977 are related to available data on the total smear-taking activity in the regions. In 1980 some 40% of women in Denmark were covered by organized screening programmes, but the total number of smears taken in the country was sufficient to cover the whole female population by an organized programme. Therefore, in order to evaluate the impact of the screening activity in Denmark account must be taken of trends in cervical cancer from areas both with and without organized programmes and of data for smears taken both in and outside the programmes. The study shows a considerable decline in the cumulative incidence of cervical cancer for women aged 30-59 in areas with organized screening programmes commenced before 1969. The decline in areas without organized programmes but with a higher or equivalent screening activity in 1974/75 is in general smaller or occurring later. In half of the areas with a lower level of smear-taking activity in 1974/75 only minor reductions in the incidence of cervical cancer are observed. Hysterectomies cannot explain the decline in the incidence for women below the age of 60. The observed pattern gives further evidence of a decline in the incidence of cervical cancer following the introduction of pap smears, but future trends should be kept under close surveillance.