Nearly 5% of lung cancer patients are asymptomatic and are only detected during chest X-ray. Most patients can show more or less symptoms and signs related to lung cancer, which can be divided into four aspects according to the location: bronchial-lung localization, extrathoracic extension, extrathoracic metastasis and non-metastatic extrathoracic manifestations. 1.Local bronchopulmonary manifestations: There is often an irritating dry cough, or what patients feel as a “smoking cough”. A few manifestations are high-pitched metallic cough or irritating choking cough. There may be intermittent or persistent hemoptysis, dyspnea and wheezing if the tumor obstructs the bronchus, and obstructive pneumonia with fever and cough. Half of the patients may have chest pain. 2.Extra-pulmonary and intra-thoracic extension manifestation: about 15% of patients have tumor growing into chest cavity, chest wall, mediastinum or invading nearby structures and nerves and causing corresponding symptoms. About 5% of patients show hoarseness and superior vena cava obstruction syndrome, manifesting as head, face and upper body bruising and edema, neck swelling and jugular vein anger, patients often complain of progressive tightening of collar, and expanded venous collateral circulation can be seen in the anterior chest wall. Patients often complain of progressive tightening of collar and dilated venous collateral circulation in anterior chest wall. 3.Extra-thoracic metastasis manifestation: 3-10% of patients can show symptoms and signs of extra-thoracic metastasis. Neurological symptoms of intracranial metastasis may be manifested, including increased intracranial pressure, such as headache, nausea, vomiting and abnormal mental status. 1%-2% of patients have pain and pathological fracture due to tumor metastasis to bone. Tumor metastasis to the spine can cause symptoms of spinal canal compression and obstruction. Small cell lung cancer may metastasize to the pancreas causing pancreatitis and obstructive jaundice symptoms. 4. Non-metastatic extrathoracic manifestations: also known as paraneoplastic syndrome. Nearly 2% of lung cancer patients are initially diagnosed because of systemic symptoms or these symptoms and signs unrelated to distant tumor metastasis, which lack specificity and mainly manifest as the following: (1) Cushing’s syndrome: 2-5% of small cell lung cancer can appear, manifesting as centripetal obesity, acromegaly, etc. (2) Antidiuretic hormone secretion: It can cause anorexia, nausea, vomiting and other water toxicity symptoms, and may also be accompanied by progressively worsening neurological complications. (3) Carcinoid syndrome: The main manifestations are flushing or edema of the face and trunk of upper limbs, enhanced gastrointestinal motility, diarrhea, tachycardia, wheezing, itching, and abnormal sensation. These manifestations are associated with vasoactive substances released from tumor cells. (4) Ectopic gonadotropin secretion: mainly manifested as gynecomastia and hyperplastic osteoarthropathy. (5) Hypoglycemia and hypercalcemia: Hypoglycemia is associated with insulin-like substances secreted by tumor cells. Hypercalcemia is caused by the presence of bone metastasis or excessive secretion of parathyroid hormone-related protein by the tumor. Patients show drowsiness, nausea, vomiting and weight loss and mental changes. It can return to normal after tumor removal. (6) Neuromuscular manifestations: cancerous neuromuscular lesions are the most common non-metastatic extrathoracic manifestations of lung cancer, with an incidence rate of nearly 15%. Half of the patients have no other lung cancer symptoms, and the neuromuscular lesions of 1/3 patients occur before the appearance of other symptoms or 1 year before the definite diagnosis of lung cancer. The main abnormalities are: cerebellar degeneration, motor neuropathy, polyneuritis combined with mixed motor and sensory disorders, sensory neuropathy, polymyositis, autonomic abnormalities, etc. If the above abnormal manifestations occur, you should go to the hospital for examination to exclude lung cancer in time.