If lung cancer is metastatic, it is the most advanced stage. If lung cancer can be cured, it must be cured by early surgical treatment and complete removal. Once it metastasizes, overall speaking, it is impossible to be completely cured because surgery is no longer effective and can only be controlled by non-surgical methods, including chemotherapy and radiotherapy. Once metastasis has occurred, all these treatments cannot completely kill every tumor in the lymphatic system, so it is impossible to do so.