Lung cancer mostly grows in the bronchial wall, and due to the growth of cancer cells, it destroys the normal tissue structure and strongly stimulates the bronchial tubes, causing cough. It cannot be well relieved by antibiotics and cough suppressants, and gradually worsens, with occasional occurrence of bloody sputum and chest pain. This kind of cough is often considered to be an early sign of lung cancer. Alert groups: Those who are older than 40 years old, those who smoke more than 400 cigarettes per year, those who have a history of tuberculosis, especially those with tuberculosis traces, and those who have a history of exposure to occupational carcinogens, such as asbestos, inorganic arsenic compounds, coal smoke, tar, and polycyclic aromatic hydrocarbons in petroleum. Measures for early detection: For high-risk groups, chest X-ray should be done once a year. If the following symptoms occur: (1) unexplained chest pain, hemoptysis sputum. (2) Inflammation recurring in the same part of the lung, with poor results after aggressive anti-inflammatory therapy. (3) Sudden relapse and worsening after stabilization of the tuberculosis patient. (4) Those with localized pulmonary emphysema or pulmonary atelectasis should be alerted and undergo bronchoscopy if necessary.