Not only targeted drugs, but all drugs used to treat tumors, including chemotherapeutic drugs, will produce drug resistance. Compared to chemotherapeutic drugs, targeted drugs can maintain to drug resistance for a longer time, also using a certain drug. The median time of drug resistance for targeted drugs is at least 1 year, and for some targets, the resistance time even reaches more than 30 months. Compared with chemotherapy, targeted drugs are less likely to develop resistance, but compared with several drugs, targeted drugs have a longer maintenance time to resistance.