There is no clear course of lung cancer targeted therapy, and the general reason for replacement is the emergence of drug resistance, or serious side effects that patients cannot tolerate and need to replace other drug therapy. In fact, EGFR, ALK and ROS1 mutations are common in lung cancer targeted therapy clinics, especially for patients with EGFR mutations, they can take a generation of oral EGFR inhibitors, such as Gefitinib, and now they often take Irico, which will become resistant after one year and need to be replaced by other targeted drugs, which can be replaced by third generation drugs, and now they are commonly used Ocitinib. If the patient is negative for T790 test and needs to be replaced with other drugs, such as immunotherapy or anti-vascular inhibitor therapy, the patient can take Ocitinib orally for up to 2-3 years. If the patient does not find tumor enlargement or distant metastasis, he can keep taking oral subtargeted therapy drugs until the disease progresses. Therefore, the general course of oral targeted therapy is one year, and if patients develop tumor enlargement, they can change to third-line targeted therapy, which can be taken orally for up to 2-3 years. If patients do not have mutated T790, they can be replaced with immunotherapy or other chemotherapy or anti-vascular inhibitor therapy.