Malignant disease of the lung, including the bronchi, is steadily assuming greater importance as the result probably both of increased frequency and of more accurate diagnosis. It is important that the effort should be made to increase our knowledge of the subject in the hope that early diagnosis and proper treatment may reduce the mortality. This hope must be concerned particularly with neoplasms originating in one part; namely, in the bronchus. The term "carcinoma of the lung" suggests a neoplasm of the lung tissue proper, but new growths originating in the lung parenchyma comprise only a small proportion of all lung tumors (perhaps from 10 to 15 per cent). The great majority originate in the bronchi and subsequently invade the lung tissue.
It is therefore with neoplasms originating in the bronchi that we are particularly concerned. The main points that we shall discuss are (1) the question of increase in