A clear diagnosis of lung cancer is not an easy task. In general, the diagnosis of lung cancer includes imaging, cytology, hematology and various invasive tests. The general principle of choosing among various diagnostic methods is to start with non-invasive examinations first, then move on to invasive examinations, and to adopt the most appropriate examination method considering the tumor location, stage and patient’s physical condition. The final diagnosis of lung cancer can be 100% confirmed only through pathological diagnosis. Let us introduce to you in detail: imaging examination Fluoroscopy and chest X-ray – advantages: simple, convenient and inexpensive. Disadvantages: difficult to detect lung cancer with diameter less than 1 cm and located in hidden areas of the chest (such as the tip of the lung, paraspinal area, mediastinum, etc.). CT examination is required to detect them. CT examination – CT degree has higher resolution, easy to determine whether there is local invasion, and is the most important examination method for early lung cancer screening. Magnetic resonance imaging (MRI) – MRI is a non-invasive, radiation-free biological imaging technique. It is mainly used for the determination of mediastinal disease and has a higher sensitivity for metastases such as the nervous system and bones. PET-CT – PET-CT is a functional test that facilitates the localization of lung lesions for qualitative diagnosis. However, it is sometimes not sensitive for early small nodular lung cancer and is not clinically preferred. Sputum exfoliative cytology examination Cytology examination is mainly sputum exfoliative cytology examination. Patients with lung cancer sometimes have some cancer cells shed in sputum, and this can also be used to confirm the diagnosis. Tumor markers In terms of hematology, there are also some tumor markers, such as squamous carcinoma antigen, CEA carcinoembryonic antigen, etc., which can be tested by blood sampling to see if there is a possibility of lung cancer. However, these tumor markers are not closely related to lung cancer, and there is no reliable serum tumor marker with high specificity for the diagnosis of lung cancer, but only a certain reference. Bronchoscopy Through bronchoscopy, the lesions of bronchial lining and lumen can be directly observed, and biopsy can be performed to obtain pathology, or bronchial secretions can be aspirated for cytological examination. The electromagnetic navigation bronchoscopy system (ENB) can be used for real-time guidance and can be used in conjunction with endobronchial ultrasound (EBUS) to obtain specimens for pathological examination. Percutaneous lung aspiration biopsy is usually performed under the guidance of chest CT and tissue biopsy is performed with a fine needle or a special puncture biopsy gun. Mediastinoscopy Mediastinoscopy is an option when the nature of the mediastinal lymph nodes cannot be confirmed by EBUS-TBNA. Surgical biopsy Surgical biopsy (thoracoscopy or open chest) should be performed when the nature of the lung mass is not clearly defined by multiple tests and short-term diagnostic treatment, and the possibility of lung cancer cannot be excluded. Other tests Other tests such as pleural fluid to detect cancer cells, ECT bone imaging, abdominal ultrasound, etc. are used to clarify whether there are distant metastases.