The Mayo Lung Project for early detection and localization of bronchogenic carcinoma: a status report.

The Mayo Lung Project (MLP) is a screening program designed to detect bronchogenic carcinoma at a curable stage. Screening tests include chest roentgenograms, three-day "pooled" sputum cytology studies, and lung-health questionnaires. These are being applied every four months to a study population of outpatients who have a high probability of developing lung cancer. Initial patient acceptance of the screening program has been excellent. Small asymptomatic lung cancers have been detected both roentgenographically and cytologically. The two procedures have complemented each other with little overlap. Chest roentgenography has proved most useful in diagnosing peripherally situated cancers, whereas sputum cytology studies have been most effective in identifying early squamous cancer involving major airways. At present, more cancers have been detected roentgenographically than cytologically, but the cytologically detected cases appear to have a better prognosis. Roentgenographically occult cancers have been localized with regularity, although the localization process is complicated. Theoretically, vigorous application of radiologic and cytologic screening, combined with optimum use of localizing procedures and treatment, could increase the five-year survival rate among lung cancer patients to nearly 50 percent. However, the actual survivorship attained will ultimately be determined by currently imponderable factors such as patient acceptance of longterm screening, frequency of multicentric respiratory cancers, and incidence of noncancerous smoking-related diseases, especially chronic obstructive pulmonary disease and ischemic heart disease.