Predilection of lung cancer for the upper lobes: an epidemiologic inquiry.

Data from 24,798 cases of primary neoplasm of the lung registered by the Surveillance, Epidemiology, and End Results Program between 1973 and 1977 were examined for the demographic determinants of lobe of origin. Lung cancer occurred predominantly in the upper lobes in both sexes, in both blacks and whites, and at all ages. This pattern was observed for squamous cell and small cell carcinoma as well as adenocarcinoma. The predominance of lung cancer in the upper lobes was much stronger in the young and somewhat stronger in blacks. These findings are discussed in light of current theories of pulmonary carcinogenesis. Current theories may not explain entirely these observed patterns, and further inquiries into this question, therefore, may be useful.