Lung cancer is a very common type of malignant tumor of the respiratory system. Stage 3a lung cancer is generally a type of intermediate and advanced stage. Generally, lung cancer is divided into stages 1-4, and each stage may be divided into a, b or c, so lung cancer stage 3a is a kind of intermediate and late stage. Once lung cancer reaches stage 3a, there may be more surrounding enlarged lymph nodes or mediastinal metastasis or intrapulmonary metastasis. However, if preoperative neoadjuvant chemotherapy or targeted therapy is considered first, it can shrink the tumor and reduce the stage, and there is still a chance for another surgical treatment later. Of course, the pathological nature of lung cancer needs to be clarified, and usually bronchoscopy or percutaneous lung aspiration biopsy is needed to obtain pathology. If surgery is not possible, radiotherapy and targeted therapy are also more effective.