Some targeted drug treatments may make the tumor disappear completely, that is, complete remission of the tumor is obtained, but most of the targeted drugs can only make the cancer partially remit, and cannot make the cancer disappear completely. A small number of patients can no longer see the original cancer lesions when they undergo imaging examinations such as ultrasound, CT or MRI after treatment with targeted drugs. After the tumor disappears completely through treatment, the survival of cancer patients can generally be significantly prolonged. However, after most patients are treated with targeted drugs, although the cancer lesions can be reduced by 1/3-1/2 or even 3/4 than before the treatment, there are still some cancer lesions left. Therefore, targeted drug therapy usually requires a long period of consolidation and maintenance to maintain the stability of the cancer condition and avoid further development of the cancer. In addition, it should be noted that targeted drug therapy, like traditional chemotherapy, can become resistant after a period of treatment. Even if the tumor disappears completely after targeted drug treatment, there are still potential cancer cells in the patient’s body. These cancer cells can re-enter the proliferation and growth cycle after the development of resistance to targeted drugs, causing the cancer to recur, and then the original targeted drugs should be stopped and genetic testing should be conducted to find out whether there are targets related to drug resistance and to guide the subsequent targeted therapy.