Symptoms: 1. Cough, sputum and hemoptysis: The most common symptom of early lung cancer is irritating cough caused by the growth of cancer under the bronchial mucosa, mostly dry cough or a small amount of white foamy sputum, which is easily mistaken for cold and flu. Patients with smoking habits often have a mild cough, which is often overlooked until the cough persists and then they seek medical examination. Another common early respiratory symptom is bloody sputum, usually with blood spots or blood shreds in the sputum, and occasionally or intermittently with small amounts of hemoptysis; massive hemoptysis is only seen in a few cases of bronchial adenoma. 2. Chest tightness and shortness of breath: when the cancer grows to cause large bronchial obstruction of different degrees or when pleural effusion appears, it may present symptoms such as chest tightness, croup and shortness of breath. 3.Fever: If the bronchial obstruction is complicated by lung inflammation or if the central part of the giant cancer is necrotic and forms cancerous cavity, there are symptoms such as fever, increased sputum and mucopurulent sputum. 4. Chest pain: mild chest pain is quite common in early lung cancer cases, mostly irregular dull pain caused by inflammation of wall pleura and chest wall; continuous and severe chest pain often indicates that the cancer has directly spread and invaded the pleura and chest wall tissue, and the cancer has entered advanced stage. 5.Symptoms of tumor metastasis: if lung cancer invades other tissues and organs in the chest from the lung, the following symptoms may appear: (1) compression or invasion of phrenic nerve causes ipsilateral diaphragm paralysis, elevation of diaphragm position, disappearance of movement or paradoxical movement, i.e. diaphragm rises when inhaling and falls when exhaling. (2) Compression or invasion of the recurrent laryngeal nerve causes paralysis of the vocal cords and hoarseness of voice. (3) Compression or invasion of superior vena cava, resulting in superior vena cava syndrome, presenting angry venous turgor in the face, neck, upper limbs and upper chest, subcutaneous tissue edema, and elevated venous pressure in upper limbs. (4) Invasion of cancer into the pleura may lead to pleural effusion, which is often hemorrhagic. Cancer cells may be found in the pleural fluid sediment. Large amount of effusion may cause shortness of breath and mediastinal shift. (5) Cancer invading the pericardium may cause pericardial effusion, and if the amount of effusion is large, it may present symptoms of pericardial pressure. (6) Cancer or mediastinal lymph node metastasis may compress the esophagus and cause dysphagia. (7) Upper lobe apical lung cancer is also called supraglottic sulcus or Pancoast tumor. The tumor growing here compresses or invades the organs and tissues located in the upper thoracic opening, such as the first rib, upper thoracic vertebra, subclavian artery and vein, brachial plexus nerve, cervical sympathetic ganglion, etc., producing severe pain in the shoulder and back that continuously worsens and extends to the ulnar side of the upper arm and forearm. Cervical sympathetic nerve syndrome such as angry edema of upper limb veins, abnormal sensation of upper limbs, motor dysfunction, hand muscle atrophy, ipsilateral upper eyelid ptosis, pupil narrowing, eye entropion, and facial anhidrosis. (8) In advanced lung cancer cases, pain and inflammatory infections caused by primary and metastatic lesions may lead to loss of appetite, shortness of breath, mental depression, physical exertion, etc., and may present emaciation and cachexia. Bronchial lung cancer has no special signs in the early stage. After the cancer grows and causes bronchial obstruction, it can show corresponding signs. If the cancer invades the extra-pulmonary tissues in the chest, there may be signs such as pleural effusion, pericardial effusion, diaphragm elevation, chest wall pressure points, compression of superior vena cava and vocal cord paralysis. Extrathoracic distant metastases may involve various parts of the body and present various physical signs. Therefore, the physical examination of lung cancer patients should be comprehensive and meticulous, paying special attention to whether there are enlarged lymph nodes in the neck, enlarged liver and other common metastatic lesions. Imaging examination can detect lung lesions at an early stage and understand the extent of lesion invasion, and provide a basis for lung cancer staging, and the commonly used methods are: 1. Frontal and lateral chest radiographs: bronchial lung cancer is divided into central type and peripheral type. Peripheral type lung cancer accounts for about 75%. Early diagnosis of central type mainly relies on cancer cytology and bronchoscopy, while X-ray plain film can show secondary obstructive changes. For the early detection of peripheral lung cancer, radiographs play an important role. Although there are many complex and advanced imaging techniques, X-ray plain film is still the preferred imaging method for lung cancer. 2.CT of the chest: In the detection of lesions, some reports point out that spiral CT is 40% more effective than X-ray plain film for the display of lung nodules. Due to the large amount of X-rays and high cost of this method, it cannot be used for routine physical examination yet. CT is the best method for the differential diagnosis of nodular masses in the lung. HRCT is able to show wall thickening and intraluminal nodules in early central lung cancer. Multiplanar reconstructions (MPRs) show the location and extent of the tumor in the long axis of the airway, the degree of airway narrowing, the distal condition and the extent of infiltration into the extraluminal lumen. Simulated bronchial endoscopy is less accurate than fiberoptic bronchoscopy for the display of bronchial mucosal palpable lesions, but is able to identify larger masses, stenoses and the distal end of stenoses in the trachea. In terms of lung cancer staging, the correct rate of CT diagnosis of hilar mediastinal lymph node metastasis is generally 60%-80%, and tumor invasion of the mediastinum is manifested by the disappearance of the mediastinal fat layer. The lumen is deformed and narrowed when the blood vessels are invaded, and the diagnostic accuracy rate is 60%-90%. If tumor invades pleura, pleural fluid and pleural nodules will appear. CT is also used to follow up the changes of lung cancer after treatment, i.e. whether the tumor has disappeared, decreased, increased, recurred or metastasized. 3.Bone scan: 3% of lung cancer patients have bone metastasis as the first symptom, and about 30%~40% of patients with progressive stage will have bone metastasis. The most commonly used bone imaging technique is radionuclide bone scan. Patients with positive lesions on bone scan, especially those with multiple bone metastases in weight-bearing bones, should undergo CT and magnetic resonance imaging (MRI) for further differential diagnosis. 4.Brain CT/MRI: Lung cancer is prone to brain metastasis, so brain examination should be performed before treatment to clarify the diagnosis, and MRI is better than CT. 5.Abdominal ultrasound: routine examination should be performed before treatment, and enhanced CT should be added to confirm when metastasis is detected. 6.B ultrasound of supraclavicular lymph nodes: routine examination should be performed before treatment, and enhanced CT should be added to confirm when metastasis is found. 7.Systemic PET: If economic conditions allow, it can be used as preoperative staging and postoperative follow-up examination, but there are some false positive results, which need comprehensive analysis. Pathological diagnosis of lung cancer plays a decisive role in the selection of its treatment plan and prognosis, therefore, pathological diagnosis is necessary before lung cancer treatment, and the commonly used methods are as follows: 1. Fiber bronchoscopy: positive detection rate of 60% to 80%, which can see masses, stenosis, ulcers, etc., and perform smear cytology, bite biopsy, local lavage, transmural biopsy of external pressure masses or mediastinal lymph nodes, etc. Obtain biopsy pathology. 2, percutaneous pulmonary puncture: adapted to peripheral lesions, with a fine needle, safer operation and fewer complications. 3, mediastinoscopy: mediastinal lymph node biopsy pathology can be obtained, which is helpful for clear diagnosis and staging. 4.Thoracoscopy: It is possible to remove or biopsy peri-pulmonary type masses to obtain pathological diagnosis. 5.Cytological examination of pleural fluid/pericardial effusion: thoracentesis or pericardial puncture to drain the effusion for cytological examination. 6.Surgical or puncture biopsy of metastatic sites: superficial metastases, such as subcutaneous metastases and lymph node metastases, can be biopsied by surgical excision; liver metastases and bone metastases can be biopsied by puncture biopsy to obtain pathology. 7.Sputum exfoliative cytology examination: simple and easy to perform, but the positive detection rate is low, and there is a false positive rate of 1% to 2%. This method is suitable for screening in high-risk groups. 8. Open-chest surgical exploration: For some patients who are difficult to diagnose, minimally invasive surgical biopsy can be used. Tumor markers: CEA, NSE, SCC, CA199, CA125, CYFRA211, etc., do not have diagnostic significance, but can be dynamically observed to understand tumor progression/remission, and can indicate disease progression before imaging (tumor markers are significantly elevated).