Cancer, lung

A malignant tumor of the lung, the major organ of respiration. Lung cancer kills more men and women than any other form of cancer. Eight out of 10 lung cancers are due to damage caused by tobacco smoke. Persistent cough and bloody sputum can be symptoms of lung cancer. Diagnosis of lung cancer can be based on examination of sputum or on tissue examination with biopsy, using bronchoscopy, a needle through the chest wall, or surgical excision.