Stage 4 of lung cancer means advanced stage of lung cancer. According to the existing international staging standards for lung cancer, lung cancer is divided into 5 stages, such as 0, 1, 2, 3, 4, etc. Stage 4 generally means that regardless of the condition of the primary tumor or the presence of lymph node metastasis, as long as there are distant metastases, it is considered stage 4. Therefore, in general, patients with stage 4 lung cancer have metastases from other organs in combination. The prognosis of such patients is generally very poor, and the treatment is mainly based on chemotherapy, while some patients can be considered to receive molecular targeted therapy according to their genetic mutations.