LUNG TUMOURS IN ICELAND

Two hundred and twenty three primary lung tumours submitted for histological diagnosis in Iceland during the period 1941–1968 were typed according to the WHO histological classification. The distribution of the four major types was: epidermoid carcinomas 20.6 per cent (males 26.4 per cent, females 10.1 per cent), small cell anaplastic carcinomas 37.2 per cent (males 39.6 per cent, females 32.9 per cent), adenocarcinomas 23.3 per cent (males 18.0 per cent, females 32.9 per cent) and large cell carcinomas 14.8 per cent (males 13.2 per cent, females 17.8 per cent). Other types constituted only 4 per cent. The low number of epidermoid carcinomas among males and the high number of small cell ana‐plastic carcinomas in both sexes is unusual. The majority of the tumours which could be localized were bronchial or central and only 12 per cent were peripheral. Based on these histologically verified lung tumours the male/female ratio was found to be decreasing from 2.5 to 1.6 over the period. If two 7 year periods were compared the rise in the incidence of lung tumours was found to be statistically significant for the combined tumour types I‐IV in both sexes and for adenocarcinomas in females. The ratio of Kreyberg Group I: II has increased for males but remained stationary for females, which throws doubt on the theory that the increase in female incidence can be attributed to smoking. The WHO classification is a practical guide to the typing of lung tumours in routine diagnostic pathology. The criteria are clear enough for the separation of the major histological types and all subtypes except those of small cell anaplastic carcinomas. The incidence of lung carcinoma in Iceland is expected to continue to rise.