Early stage lung cancer includes in situ cancer, but not all of them are in situ cancer. In situ cancer should be the earliest type of early stage lung cancer, which can be cured by surgical removal of in situ cancer and does not require other treatments such as radiotherapy and chemotherapy after surgery, as long as it is reviewed regularly. Besides in situ cancer, other tumors in the early stage of lung cancer usually do not require radiotherapy after surgery because they do not have regional lymph node metastasis. However, if there are factors with poor prognosis, such as undifferentiated or hypodifferentiated tumors, vascular invasion, nerve invasion, etc., adjuvant chemotherapy is generally needed after surgery, which can reduce the chance of recurrence and metastasis in the future, thus increasing the cure rate of early stage lung cancer.