Tumours in Iceland. 5. Malignant tumours of the cervix uteri. Histological types, clinical stages and the effect of mass screening.

The histological material from patients with invasive cervical carcinoma diagnosed in Iceland during the period 1955-1974 was reviewed and retyped in accordance with the WHO classification of tumours. Out of 314 malignant epithelial tumours 86.0 per cent were squamous carcinomas (subtypes: 6% microcarcinomas, 30% keratinizing, 45% non keratinizing and 5% small cell carcinomas), 9.0 per cent adenosquamous carcinoma, 3.5% adenocarcinoma and 1.5 per cent undifferentiated carcinoma. A mass screening for uterine cancer in the population, ages 25-59, led to an increased incidence of cervical carcinoma, due to the finding of early tumours (clinical stages IA and IB). The increase was most marked in the first five years of screening (1965-69). The screening did not increase the incidence of the more advanced stages and a longer observation will be needed to determine whether a decline will occur in such tumours. All the major histological types of cervical carcinoma appear to progress at the same rate through the clinical stages, from the early to the far advanced.