About 5%-10% of early stage lung cancer patients have no symptoms and are only detected during X-ray physical examination. 90% of patients have symptoms, but they are not early specific symptoms and can be broadly classified into 4 categories. 1. Lung symptoms: (1) Cough: It is the most common symptom and about 2/3 of patients have this symptom. It can be a mild dry cough or a severe cough with varying amounts of sputum. However, in patients with chronic long-term cough once the nature of cough changes or frequency or nocturnal cough appears, be alert to lung cancer. Persistent and uncontrollable cough is one of the most painful symptoms of lung cancer. (2) Hemoptysis: half of the lung cancer patients have this symptom. once smoking men over 40 years old have blood in sputum, blood or small blood clots, the possibility of lung cancer is quite high, which is also one of the early symptoms of lung cancer. (3) Chest pain: 30% to 40% of patients have pulmonary chest pain, which is generally intermittent and not severe pain in the chest. It is dull pain or drilling pain, which can last for several minutes to several hours. If the cancer invades the pleura, the pain is more intense, persistent and fixed. If early stage lung cancer reproduces chest pain, and the pain appears again later, it means poor prognosis. (4) Fever: Most of the fever in lung cancer is caused by inflammation due to obstruction of bronchial cavity and poor drainage caused by cancer. Early treatment with antibiotics can restore the body temperature to normal, but it is easy to recur. In larger tumors, necrosis occurs in the inflammatory center and often causes higher body temperature due to the absorption of toxins. Sometimes daily flaccid fever for several months, repeated anti-inflammatory treatment is ineffective, once the tumor is removed, the body temperature immediately returns to normal. Patients with lung cancer have no obvious inflammation in the body, but have obvious fever, which is often caused by the tumor itself, that is, the so-called “cancer fever”, and the body temperature is often below 38c. Male smokers over 45 years old who have long-term inflammatory fever in the lungs and have poor treatment results should be especially alert to the possibility of lung cancer. (5) Chest tightness and shortness of breath: except for tumor obstruction of bronchus causing pulmonary atelectasis and inflammation of lung which can cause chest tightness and shortness of breath, it is usually more obvious in the late stage of lung cancer, especially when there is a lot of pleural fluid. 2.Extra-pulmonary and intra-thoracic manifestations: As the tumor invades the pleura, chest wall, mediastinal organs and intrathoracic nerves, it can cause a series of chest manifestations. Tumor invasion of pleura can cause breathing pain and pleural effusion (i.e. pleural fluid), and bloody pleural fluid means bad prognosis. If malignant tumor cells are found in the pleural fluid, the chance of surgery will be lost. The involvement of tumor in mediastinum is mostly caused by mediastinal lymph node metastasis, but few of them are direct invasion. In 5% of patients, tumor compression of superior vena cava causes swelling of upper limbs and shoulders, venous anger, headache and difficulty in breathing, which indicates advanced stage. Tumor compression on esophagus can cause difficulty in swallowing, and invasion of laryngeal nerve can cause hoarseness. 3.Extra-thoracic metastasis: lung cancer often metastasizes along lymphatic vessels and blood vessels, and metastasis to cervical lymph nodes, liver, adrenal gland, bone, kidney and brain is common. Nearly 15% of patients have metastases as the earliest manifestation, and hematogenous metastases are most common in adenocarcinoma and small cell lung cancer. 4. Extrathoracic non-metastatic manifestations: Extrathoracic non-metastatic manifestations can occur in only 2% of patients, but the symptoms are complex, involving more systems and the etiology mechanism is unknown. Commonly, there are skeletal manifestations, such as pestle finger (toe) and osteoarthropathy, etc.; neuromuscular manifestations, such as myopathy, peripheral neuropathy, cerebellar degeneration, etc.; endocrine manifestations, such as Cushing’s syndrome, abnormal hormone secretion, carcinoid syndrome, hypercalcemia, etc.; vascular manifestations, such as phlebitis, endocarditis, etc.; hematological manifestations, such as anemia, purpura, leukemia-like reaction, etc.; skin manifestations, such as acanthosis nigricans, scleroderma, etc. Scleroderma, etc. Systemic manifestations: like other malignant tumors, systemic manifestations of lung cancer may include anorexia, emaciation, weakness, and finally cachexia.