Molecular targeted therapy is no longer a new term in the 21st century. In recent years, with the remarkable efficacy of new molecularly targeted drugs in clinical practice, it has demonstrated the correctness and feasibility of the theory of molecularly targeted therapy, which has pushed cancer treatment to an unprecedented new stage. I. Definition of molecular targeting therapy Molecular targeting therapy refers to the therapeutic means that target the cell signaling and biological pathways involved in the process of tumor development. Broadly speaking, molecular targets include any subcellular molecules from DNA to protein/enzyme level that are involved in tumor cell differentiation, cycle, apoptosis, cell migration, infiltration behavior, lymphatic metastasis, systemic metastasis and other processes. II. Difference between targeted therapy and chemotherapy Anti-tumor drugs can affect both normal cells and tumor cells after entering the body. Although both types of cells can die due to irreversible cell damage caused by chemotherapy drugs, normal cells have stronger repair ability and can continue to survive if the damage is small. Targeted therapy only targets tumor cells with altered characteristics, which reduces the damage to normal cells while exerting stronger anti-tumor activity. Therefore, targeted therapy is less likely to cause a series of toxic side effects caused by chemotherapy drugs. At present, the more mature targeted drugs in clinical use are 1, Merova (rituximab): has been successfully applied to CD20 positive non-Hodgkin’s lymphoma; 2, Gleevec (Imatinib metavanadate): has been successfully applied to gastrointestinal mesenchymal tumor; 3, ERSA (Gefitinib) and Troche (Erlotinib): has been successfully applied to the treatment of advanced non-small cell lung cancer; 4, Epiduo (cetuximab ): Combined chemoradiotherapy has been successfully applied in the treatment of advanced head and neck tumors and Kras wild-type advanced colorectal cancer; 5. Herceptin (trastuzumab): Combined chemotherapy has been successfully applied in the adjuvant chemotherapy and first-line treatment of HER-2-positive breast cancer and HER-2-positive advanced gastric cancer; 6. Vetin (bevacizumab): Combined chemotherapy has been applied in the treatment of advanced colorectal cancer; it can also be used in the treatment of advanced 7. Doxorubicin (Sorafenib): successfully used in the treatment of advanced kidney cancer and primary liver cancer; 8. Sotan (Sunitinib malate): successfully used in the treatment of gastrointestinal mesenchymal tumor and advanced kidney cancer. All of the above drugs have been successfully marketed in China and have been widely used in the treatment of various tumors. It is believed that with the development of scientific research, there will be more and more effective targeted drugs to bring hope to tumor patients in the future!