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Cigarette-smoking males (6,364), aged 40-64, were randomized into an intervention group which received 6-monthly screening by chest X-ray and sputum cytology, and a control group which received no asymptomatic investigation. After 3 years, both groups entered a follow-up period during which they received annual chest X-rays. Lung cancer cases detected by screening were identified at an earlier stage, more often resectable, and had a significantly better survival than "interval" cases diagnosed mainly because of symptoms. Comparison of the 2 groups showed a higher incidence of lung cancer in the intervention group, despite the follow-up period when both groups received annual examinations. There was no significant difference in mortality between the 2 groups.

A randomized prospective study of lung cancer detection was begun in 1976 to evaluate semiannual screening by radiologic and sputum cytologic study in comparison to screening at a 3-year interval, and to no screening. In a high-risk population of 6364 men (aged 40 to 64 years), the initial prevalence of lung cancer was 0.28% (18 cases), the annual incidence was 0.35% per year (66 cases during 3 years), the proportion of Stage I cases was 31% (26/84), and Stage I1 was 17% (14/84), "curative" resections were 27% (23/84), and 5-year survival was 23% (19/84). The study confirmed the ability of radiologic screening to detect lung cancer a t an earlier stage when treatment by resection can be accomplished. The fate of a high-risk population submitted to screening was better than that of a population with no screening where lung cancer was discovered by symptoms, accidental x-rays, or a t autopsy. A matter of lesser importance was the frequency of screening. The absolute numbers of 5-year survivors detected by screening were practically the same for either compared screening frequency.

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