Smoking, sputum, and lung cancer.
D000328:Adult; D003371:Cough / Q000209:etiology; D006801:Humans; D008175:Lung Neoplasms / Q000453:epidemiology*; D008297:Male; D008400:Mass Chest X-Ray; D008875:Middle Aged; D012907:Smoking; D013183:Sputum