The National Cancer Institute of the United States recently sponsored three large-scale, randomized controlled trials of screening for early lung cancer. The trials were conducted at the Johns Hopkins Medical Institutions, the Memorial Sloan-Kettering Cancer Center, and the Mayo Clinic. Participants were middle-aged and older men who were chronic heavy cigarette smokers and thus at high risk of developing lung cancer. Screening procedures were chest radiography and sputum cytology, the only screening tests of established value for detecting early stage, asymptomatic lung cancer. In the Hopkins and Memorial trials the study population was offered yearly chest radiography plus sputum cytology every 4 months. The control population was offered yearly chest radiography only. In these trials the addition of sputum cytology appeared to confer no lung cancer mortality rate advantage. The Mayo Clinic trial compared offering chest radiography and sputum cytology every 4 months to offering advice that the two tests be obtained once a year. This trial demonstrated significantly increased lung cancer detection, resectability, and survivorship in the group offered screening every 4 months compared with the control group. However, there was no significant difference in lung cancer mortality rate between the two groups. The statistical power of these trials was somewhat limited. Nevertheless, results do not justify recommending large-scale radiologic or cytologic screening for early lung cancer at this time.
A detailed study was made of the chest radiographs of 600 patients with bronchogenic carcinoma who had had thoracotomy or intensive radiotherapy. Tumours of the various histological cell types tended to present with different radiographic patterns. Squamous-cell carcinoma was most often characterized by bronchial obstruction, often in association with a hilar mass. Squamous-cell lesions also were far more likely to show cavitation than were lesions of the other cell types. Small-cell carcinoma had a higher percentage of hilar masses than did other tumours but showed less tendency than did squamous-cell carcinoma to produce obstruction in association with the hilar mass. Adenocarcinoma most often presented as a peripheral mass as did large-cell carcinoma.
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