Tumours in Iceland. 17. Malignant tumours of the oesophagus. Histological classification and epidemiological considerations.

We studied all primary malignancies of the oesophagus diagnosed in Iceland between 1955 and 1984 and reclassified tumours where histological material was available using the WHO classification system. Of a total of 329 tumours diagnosed in the time period, seven were excluded for various reasons. Of the remaining 322 tumours, 178 were in males and 144 in females. The age standardized incidence was 5.3/10(5) for males and 3.1/10(5) for females. The incidence of oesophageal tumours decreased for both sexes during the time period under investigation. Of 250 reclassified tumours (142 in males and 108 in females), squamous cell carcinomas comprised 81.6%. If the undifferentiated tumours are excluded, the squamous group accounted for 89.1% of the remaining tumours. Small cell carcinomas comprised 3.2% of all cases, which was higher than expected. Most of the tumours appear to be located in the middle part of the oesophagus. The vast majority of resected tumours extended through the wall of the oesophagus. A relatively higher proportion of tumours was confined to the submucosal or muscular layers in the latter half of the period. In conclusion, the epidemiological data in our study appear to resemble what is observed in the other Nordic countries for oesophageal tumours, except for slightly higher overall incidence in Iceland, especially for women.