To clarify the radiographic features of early lung cancer, the author investigated annual chest radiographs of 234 patients with lung cancer detected by mass screening. Abnormality could be detected on the previous radiographs in 79% of the patients when reviewed retrospec-tively. The causes for failing to detect the tumor on the previous examination were as follows : 1) It was too small or too faint to detect. 2) It overlapapped with other organs such as vessels or ribs or coexisted with the preceding pulmonary lesions. 3) In some instances, only a linear (non-tumorous) shadow was initially present on chest radiograph. These results indicate that systematic and careful reading of chest radiograph and compara-tive reading with the previous films are necessary, and that it is important to learn the causes for failing to detect the tumor shadow.
Early chest x-ray findings