The initial symptoms of lung cancer include: 1. long-term chronic cough without improvement after treatment; 2. people over 40 years old who smoke or passive smokers with blood in sputum or small blood clots are alert to the occurrence of lung cancer; early peripheral lung cancer may cause dull pain or hidden pain; 3. a few lung cancer tissues produce endocrine secretions; 4. before the appearance of lung lesions, they may show non-metastatic systemic symptoms; 5. Cushing’s syndrome without obvious causes, myasthenia gravis, generalized muscular neuralgia, etc. promptly visit hospitals.