X-ray examination The site and size of lung cancer can be understood through X-ray examination. Localized emphysema, pulmonary atelectasis or infiltrative lesions in the adjacent parts of the lesion or inflammation of the lung due to bronchial obstruction may be seen. Bronchoscopy allows direct visualization of the lesions in the bronchial lining and lumen. Tumor tissues can be taken for pathological examination or bronchial secretions can be aspirated for cytological examination to clarify the diagnosis and determine the histological type. Sputum cytology examination is a simple and effective method for lung cancer screening and diagnosis, and most patients with primary lung cancer can find shed cancer cells in sputum. The positive rate of sputum cytology examination for central lung cancer can reach 70% to 90%, while the positive rate of sputum examination for peripheral lung cancer is only about 50%. Thoracotomy If the nature of the lung mass is still not clear after multiple examinations and short-term diagnostic treatment, and the possibility of lung cancer cannot be excluded, a thoracotomy should be performed. This can avoid delaying the disease and losing the chance of early treatment for lung cancer patients. ECT examination ECT bone imaging can detect bone metastases at an early stage, and both X-ray and bone imaging have positive findings. It should be noted that the false-positive rate of ECT bone imaging for the diagnosis of bone metastasis of lung cancer can reach 20% to 30%, so those who have positive ECT bone imaging need to have MRI scan of the positive area. Mediastinoscopy Mediastinoscopy is mainly used for patients with mediastinal lymph node metastasis, who are not suitable for surgical treatment and cannot be diagnosed pathologically by other methods. Mediastinoscopy is performed under general anesthesia. A transverse incision is made in the superior sternal recess, the anterior soft tissues of the neck are bluntly separated to reach the anterior tracheal space, the anterior tracheal passage is bluntly freed, and a viewing scope is placed to slowly pass behind the innominate artery to observe the enlarged lymph nodes in the paratracheal, tracheobronchial angles and under the bulge. The diagnosis of primary bronchopulmonary cancer is based on symptoms, signs, imaging and sputum cancer cell examination.