Spitting brown sputum is not necessarily a precursor of lung cancer, but may also be associated with lung infection, pulmonary tuberculosis, etc. Therefore, it needs to be clarified in combination with other symptoms and examination. Early stage of lung cancer will show symptoms such as coughing, coughing sputum, coughing with blood, chest pain, shortness of breath, etc., and may show symptoms of spitting brown sputum, but the diagnosis cannot be confirmed by a certain symptom alone, and needs to be confirmed by checking tumor markers, sputum for tumor cells, chest CT and other examinations in hospital. Spitting up brown sputum may also be caused by lung infection, which requires anti-infection treatment under the guidance of doctors. If spitting up brown sputum is caused by tuberculosis, anti-tuberculosis treatment is needed. In addition, spitting up brown sputum may also occur by consuming special drugs and foods, smoking, environmental pollution, chemical substance irritation damage, etc. Therefore, when this symptom appears, do not blindly self-diagnose, and go to hospital for detailed examination in time to exclude tumor. In daily life, you should smoke less, drink less, get away from dust polluted environment and have regular medical checkup. In diet, we should pay attention not to eat spicy and stimulating food frequently, and eat more protein-rich food and vitamin-rich fruits. Develop good work and rest habits and don’t stay up late often.