After lung cancer is suspected through clinical symptoms and chest X-ray, patients need further examination to clarify the diagnostic stage of lung cancer: First, qualitative examination, that is, whether they have lung cancer or not? The methods of examination are as follows: sputum examination, tracheoscopy, mediastinoscopy, puncture biopsy, pleural fluid drainage cytology, open-chest biopsy and exploratory surgery, etc. The diagnosis of lung cancer can be clarified by obtaining tumor tissues or cells for pathological analysis. PET-CT, and bone scan to clarify the location of lung cancer and whether there is metastasis and the site of metastasis. In addition, blood tumor markers, such as CEA, NSE, CA125, etc. are also needed to help the diagnosis of lung cancer.