Lung Cancer Basics

Lung cancer begins when abnormal cells in the bronchial or alveolar tissues multiply without normal growth control. A tumour may narrow an airway, invade nearby structures, cause bleeding, or stimulate pleural-fluid formation. Spread through lymphatic or blood vessels produces disease in lymph nodes and distant organs, so the same patient may have both respiratory symptoms and bone, neurologic, or constitutional findings. Non-small-cell lung cancer (NSCLC) is the more common group. Small-cell lung cancer (SCLC) generally grows and spreads more rapidly, which helps explain why treatment decisions depend heavily on both histology and stage. Early disease may cause no symptoms. As a tumour enlarges, common findings include a persistent or changing cough, hemoptysis, dyspnea, wheeze, chest discomfort, hoarseness, recurrent pneumonia in the same area, fatigue, anorexia, and unintentional weight loss. These findings are not specific to cancer: COPD, infection, pulmonary embolism, and heart failure can look similar. A cough that is new, progressive, associated with blood, or different from a patient’s usual COPD cough deserves assessment rather than reassurance. Risk rises with tobacco exposure, second-hand smoke, radon, and occupational inhalants such...