Pulmonary carcinoma in situ is the earliest stage of lung cancer and clinically belongs to stage 0. Pulmonary carcinoma in situ often has not yet broken through the basement membrane and has not yet had the opportunity to contact the surrounding blood vessels and lymphatic vessels, so local lymph node metastasis and distant metastasis will not occur. At this time, the tumor can be cured by surgical resection, and adjuvant radiotherapy and chemotherapy are not needed after surgery, but regular review is still needed after surgery because the remaining lung may reappear as primary lung cancer. Lung cancer includes other clinical stages besides primary lung cancer. The remaining clinical stages are I-IV, at which time the treatment needs to be based on different pathological types, and different clinical stages, to adopt different treatments such as surgery, chemotherapy, radiotherapy, targeted drug therapy, immunotherapy, etc.