There is usually no obvious precursor before getting lung cancer. Early stage of lung cancer can be manifested as chronic cough, fever, blood in sputum and so on. 1. Chronic cough: patients may show persistent and long time cough, with no effect of antibiotics, little or no sputum, irritating and repeated dry cough, metallic tone cough. 2. Fever: Fever is a common symptom of cancer, which is manifested as repeated fever. 3. Blood in sputum: Early symptoms of lung cancer may manifest as blood in sputum and occasionally hemoptysis. In order to understand the condition, patients should do chest imaging examination, tumor marker, blood routine, pathological biopsy and so on. Patients should actively consult the doctor if the above symptoms occur. Individualized diagnosis and treatment plan should be formulated according to the specific situation, so as to avoid delaying the condition.