Histological typing of lung cancer. Application of the World Health Organization classification to 479 cases.

Four hundred and seventy nine primary lung cancers were typed according to the WHO histological classification. The character of the material and the methods of investigation are described. All patients had been subjected to mediastinoscopy and 313 patients had been operated upon. Nearly half of the tumours (48 per cent) was epidermoid carcinomas. Small cell anaplastic carcinoma occurred in 25 per cent and around two thirds of these were of oat cell type. Adenocarcinoma was found in 22 per cent and the acinar type predominated. Bronchiolo-alveolar carcinoma occurred in 1 per cent and large cell carcinoma in 3 per cent. Typing of biopsy specimens was made in 289 cases in which a positive biopsy had been obtained during the pretreatment period. The result of the biopsy typing was checked against that of the final one. In the total group the preoperative histological diagnosis tallied with the final one in 88 per cent. In patients who had been subjected to surgery the pretreatment diagnosis of the epidermoid carcinoma was correct in 86 per cent, that of small cell anaplastic carcinoma in 92 per cent and that of adenocarcinoma in 100 per cent. The consistency was also high in the category of patients not subjected to surgery. Despite their critical attitude towards the delimitation of epidermoid carcinoma in the WHO-classification the present authors find it to be a reliable guide to routine typing of lung cancer.