The effect of mass screening on incidence and mortality of squamous and adenocarcinoma of cervix uteri.

OBJECTIVE: To describe the efficacy of the Finnish mass screening program for cervical squamous carcinoma and adenocarcinoma, as reflected by changes of incidence and mortality rate.

METHODS: Cervical cancer incidence and mortality data were obtained from the Finnish Cancer Registry. Data were available from the year 1953, when the registry was established. The nationwide mass screening program in Finland was started in the mid-1960s. A centralized organization administers this program. Women age 30-60 years are notified for screening every 5 years.

RESULTS: The mean incidence of cervical carcinoma in the early 1960s was 15.4 per 10(5) woman-years. In 1991, it was only 2.7 per 10(5) woman-years. The mortality rate has decreased in the same proportion since the mass screening program. In the early 1960s, the mortality was 6.6 and in 1991 1.4 per 10(5) woman-years. However, the decrease of the incidence is seen almost exclusively in squamous cell carcinomas. The mortality caused by adenocarcinoma has decreased in screened birth cohorts, but the incidence rate has remained the same.

CONCLUSIONS: The Finnish mass screening program has been effective and its continuation is of utmost importance. In the future more attention should be given to glandular cell atypias in cervical smears. Thus, it might be possible to decrease the incidence of cervical adenocarcinoma.