If lung cancer causes multiple lesions in two lungs at the same time, there are two situations: First, the most common is that lung cancer has intrapulmonary metastasis, after all, lung cancer is a malignant tumor and will metastasize distantly. That is, it can metastasize to other organs such as bones, brain, liver, etc., and also to the contralateral lung. If there is metastasis to the contralateral lung, it is still considered advanced lung cancer. In this case, surgery is not considered, and treatment is mainly through radical radiotherapy, chemotherapy and targeted therapy. Second, and relatively rare, is multiple primary lung cancer, which means that there are different primary sites on two lungs, appearing on the left or right lung at the same time. The identification of the two cases is most often based on pathological testing, which is based on the protein expression of the different lesions. The treatments for the two are different. If there are lung cancer lesions on both lungs, the pathological examination must be perfected.