Tumours in Iceland. 9. Malignant tumours of the ovary. A histological classification, epidemiological considerations and survival.

Abstract

In the period 1955-1979, 337 patients with carcinoma of the ovary were reported to the Icelandic Cancer Registry. Sufficient histological material existed for 314 of these to make it possible to classify the tumours according to the Histological Typing of Ovarian Tumours of WHO (11). The tumour was in the right ovary in 85 and the left in another 85 patients. In 137 patients both ovaries were involved at the time of diagnosis and in 30 patients the side was not known. The most frequent tumours were the group of serous adenocarcinomas, papillary adenocarcinomas and papillary cystadenocarcinomas (IA3a), occurring in 113 patients, giving an age-standardized incidence of 4.4 per 100.000. Second in frequency was the endometrioid adenocarcinoma (IC3a1), in 58 patients, and the third the group of mucinous adenocarcinoma and cystadenocarcinomas (IB3a) in 43 patients. The fourth type in frequency was undifferentiated carcinoma (IG) in 18 patients. During the period, the overall incidence of ovarian cancer did not change. However, there was an increase in the frequency of mucinous and endometrioid types of carcinoma and a decrease in serous carcinoma. Granulosa cell carcinoma was found to have been under-reported to the Icelandic Cancer Registry. ABO blood groups for 192 of the patients were available and showed a significant excess of blood group A, with patients of blood group B significantly fewer than expected. This study of malignant tumours of the ovary is the ninth in a series of investigations into the histological classification of tumours occurring in Iceland during the 20-year period between 1955 and 1974. The tumours occurring in the period 1975-1979 were included in this particular study to increase the number available for classification.