Milton B. Rosenblatt

Classification of Lung Cancer—to be Revised

To the Editor:— The accuracy of lung cancer mortality data challenged inThe Journal( 198 :1374, 1966; 199 :674, 1967) may be considerably improved by the Eighth Revision of the International Classification of Causes of Death. The present nomenclature lists malignant neoplasm of bronchus and trachea and of lung, specified as primary (code No. 162), and malignant neoplasm of lung, unspecified as to whether primary or secondary (code No. 163). The latter category was always included in the tabulation of lung cancer mortality but uncertainty has existed as to whether the medical certifier had omitted primary specification because of the possibility that the pulmonary cancer was a metastasis from an occult extrathoracic primary site. Beginning Jan 1, 1968, there will be implemented a new nomenclature. All cases of lung cancer will be considered of primary origin (code No. 162) unless the certifier specifically designates that the tumor is of secondary