I. Blood biochemical examination For primary lung cancer, there is no specific blood biochemical examination. For lung cancer patients, elevated blood alkaline phosphatase or blood calcium may be considered as bone metastasis, and elevated blood alkaline phosphatase, glutamic transaminase, lactate dehydrogenase or bilirubin may be considered as liver metastasis. Tumor marker examination 1. CEA: 30%-70% of lung cancer patients have abnormally high level of CEA in serum, but it is mainly found in patients with more advanced lung cancer. At present, the examination of CEA in serum is mainly used to estimate the prognosis of lung cancer and to monitor the treatment process. 2.NSE: It is the preferred marker for small cell lung cancer, used for diagnosis of small cell lung cancer and monitoring treatment response, with different reference values depending on the detection method and reagents used. CYFRA21-1: It is the preferred marker for non-small cell lung cancer and has a sensitivity of up to 60% for the diagnosis of squamous lung cancer, with different reference values depending on the detection method and reagents used. Imaging examination 1. Chest X-ray examination: it should include frontal and lateral chest films. In primary hospitals, frontal and lateral chest radiographs are still the most basic and preferred diagnostic imaging methods for primary diagnosis of lung cancer. Once lung cancer is diagnosed or suspected, chest CT examination should be performed. 2.CT examination: Chest CT is the most common and important examination method for lung cancer, which is used for diagnosis and differential diagnosis, staging and post-treatment follow-up of lung cancer. The scope of CT scan of the chest should include the adrenal glands when lung cancer patients are scanned in hospitals with conditions. Enhanced scan should be used as much as possible, especially for patients with central lung lesions. In addition, CT is the basic examination method to show brain metastases. Patients with clinical symptoms or progressing stage should have brain CT scan, and enhanced scan should be used as much as possible. 3.Ultrasound examination: It is mainly used to find out whether there are metastases in important abdominal organs and abdominal cavity and retroperitoneal lymph nodes, and also for the examination of lymph nodes in the neck. For intrapulmonary lesions or chest wall lesions adjacent to the chest wall, cystic solidity can be identified and ultrasound-guided puncture biopsy can be performed; ultrasound is also commonly used to locate pleural fluid extraction. 4.Bone scan: It is more sensitive to detect bone metastasis of lung cancer, but has a certain false positive rate. It can be used in the following cases: preoperative examination of lung cancer; patients with local symptoms. 5.Further examination: ① Difficult cases; ② Patients request for more comprehensive imaging examination; ③ When further imaging examination is clinically required: for example, to determine whether the chest wall or mediastinum is invaded; to show the extent of supraglottic sulcus; to identify tumor recurrence, fibrosis after radiation therapy; to exclude intracranial metastasis, etc. MRI is required.