Chronic cough with blood or blood in sputum for more than three months, untreated hydrothorax, especially bloody hydrothorax, after anti-inflammatory treatment, the shadow of chest radiographs does not subside, etc. The first precursor of lung cancer is usually a cough, and the most common case is that smokers are coughing more and more seriously. This disease is closely related to chronic bronchitis. At least half of the people who suffer from lung cancer have chronic bronchitis for years. In addition to coughing, patients will have sputum with blood in it. You may also have a mild case of dyspnea. You will often have chest pain. This pain may be sharp when you take a deep breath, or it may be dull and persistent. Sometimes you may also experience wheezing. The following early precursors and signs are helpful for early diagnosis of lung cancer: 1. Sudden dry cough, choking cough for more than two weeks and ineffective anti-inflammatory treatment, or sudden change in the nature of the original chronic cough; 2. Sudden blood in the sputum and intolerable chest pain without obvious explanation of the cause; 3. Lung auscultation, with limited rales, flutters, and snoring sounds that do not change due to coughing; 4. Repeated inflammatory changes in a certain place of lung Inflammatory changes; 5. Limited increase in lung texture or limited emphysema that cannot be explained by generalized bronchitis; 6. Long-term smokers with altered cough and blood in the sputum. There are 5%-15% of patients who have no precursor when discovering lung cancer, which shows that the early precursor of lung cancer is not obvious, and the main symptoms in the early stage may include the following aspects: 1. Symptoms caused by primary tumor: 1. cough: a common symptom in the early stage. 2. hemoptysis. 3. wheezing. 4. chest tightness and shortness of breath. 5. weight loss: emaciation is one of the common symptoms of tumors. 6. fever. Symptoms caused by local expansion of the tumor: 1) chest pain. 2) dyspnea. 3) dysphagia. 4) hoarseness. 5) superior vena cava compression syndrome. 6) Hner's syndrome. Other symptoms are not listed. To detect lung cancer at early stage, one should go to the hospital regularly for examination

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