The symptoms and precursors of lung cancer are related to whether lung cancer has metastasized or not, and the progression of lung cancer. The progression of lung cancer includes primary lung cancer, intrathoracic extension of primary lung cancer, and metastasis to other parts of lung cancer, and the symptoms and precursors are mainly as follows: I. Symptoms: 1. Primary lung cancer: Patients with primary lung cancer often have symptoms of cough and sputum, which are manifested as irritating dry cough, and the effect of taking cough suppressant is not obvious, accompanied by yellow pus sputum when combined with infection. Patients may also suffer from hemoptysis, which is often accompanied by hemoptysis when coughing, blood in sputum or bright red blood. Due to the growth of cancer cells, normal respiratory function may be reduced, resulting in symptoms such as chest tightness and breath-holding. 2. Intrathoracic extension of primary lung cancer: Patients may have hoarseness due to the compression of the recurrent laryngeal nerve by the cancer. It may also be due to the metastasis of lung cancer cells to the mediastinum, forming mediastinal tumors or enlarged mediastinal lymph nodes, resulting in compression of the esophagus and symptoms of dysphagia. The sympathetic nerve innervating the head and face may also be compressed by cancer cells, resulting in the symptoms of Horner’s syndrome, such as shrinking of ipsilateral pupil and lid fissure, no or little sweating on the ipsilateral side, sunken eyes, ptosis, etc.; 3. Lung cancer metastasis: Lung cancer cells metastasizing to the corresponding tissues or organs will produce corresponding dysfunction, such as metastasis to the thoracic spine, forming bone tumor, which will cause pain in the thoracic spine, etc. II. Precursors: The following precursors can appear at various stages of lung cancer progression: 1. Chronic cough: patients often exhibit chronic, persistent irritating repeated dry cough without or with little sputum, with high-pitched metallic sound; 2. Fever: fever of lung cancer is mostly around 38℃, which can be relieved after anti-inflammatory treatment, but it is easy to recur; 3. Hemoptysis: mostly blood in sputum or intermittent bloody sputum, and occasionally hemoptysis; 4. Dyspnea: patients may show chest tightness and shortness of breath, and some patients may have chest pain; 5. Lymph node enlargement: patients may have unexplained lymph node enlargement; 6.