Theoretically, even if early stage lung cancer has undergone radical surgery and radiotherapy, long-term survival up to 5 years or more still has the possibility of recurrence and distant metastasis, which is the terrible thing about malignant tumors. Therefore, standardized follow-up after standardized treatment is very necessary to detect tiny recurrence foci or metastases in advance so that new treatment can be started early. Never take it lightly because the disease is temporarily stabilized and neglect regular follow-up and close observation. Usually, the recommended follow-up frequency is once every six months for the first two years after treatment, and at least once a year thereafter.