Chemotherapy is a method of treating malignant tumors with anti-cancer drugs. These drugs act at different points of cell growth and proliferation to inhibit or kill cancer cells. Radical surgery has long been the common treatment for breast cancer both at home and abroad. However, since the 1950s, the efficacy of traditional radical surgery has been contested because although surgery controls the primary cancer, surgical treatment alone cannot control the recurrence and metastasis of the tumor, and about half of the patients eventually develop distant metastasis after surgery. Clinical observation shows that breast cancer is a kind of malignant tumor that is prone to hematogenous metastasis, and its hematogenous metastasis can occur at a relatively early stage of the clinical process, and it is inferred that more than half of the patients have already undergone hematogenous metastasis at the time of consultation, but it is difficult to detect it with some current diagnostic methods. Therefore, although the primary cancer is completely removed, the microscopic metastases distributed in the body will continue to grow and eventually cause adverse consequences. According to the biological and immunological studies of breast cancer, breast cancer is a systemic disease characterized by multicentric occurrence, and there are often tiny metastatic foci even when the primary foci are very small at the early stage of development. Based on the above, the treatment of breast cancer must target both primary cancer and hematogenous metastasis, i.e. a combination of local treatment and systemic chemotherapy must be adopted in order to fully control the development of breast cancer, without one of them, it is difficult to achieve the goal of curing breast cancer. The so-called systemic chemotherapy and local chemotherapy are divided according to the different methods and routes of drug administration and the distribution of drugs in the body and tumor area after administration. The main feature of systemic chemotherapy is that the drugs are absorbed through the gastrointestinal tract or enter the body through intravenous channels, and the drugs can reach all tissues and organs, and the concentration of chemotherapy drugs in tumor tissues is not significantly different from other tissues. Local chemotherapy includes local injection of tumor, arterial perfusion, intra-cavity injection, etc. Intra-arterial infusion chemotherapy can be used for breast cancer with liver and brain metastases (note: it is rarely used in practice, for reference only); intracavitary chemotherapy can be used for breast cancer with pleural, peritoneal and pericardial metastases accompanied by pleural fluid, ascites and pericardial effusion. Local chemotherapy can increase the local concentration of drugs, give full play to the efficacy of chemotherapy drugs and reduce the toxic effects of chemotherapy drugs, which has obvious near-term efficacy but poor long-term efficacy. It has been accepted that breast cancer is a systemic disease. Recent biological studies have shown that breast cancer multiplies from a single cell division to a lump of 1 cm in diameter, multiplying 30 times and growing for at least 3 years (note: different statements here), which provides enough time for systemic blood dissemination, thus systemic treatment has been paid more and more attention. Currently, in the treatment of breast cancer, chemotherapy is required for almost all stages of patients except for stage 0 and some stage I patients. The purpose of post-surgical chemotherapy is to reduce distant dissemination and thus improve the long-term outcome. Breast cancer is one of the most effective tumors among solid tumors in which chemotherapy is applied, and the anti-cancer drugs for the treatment of breast cancer are developing rapidly, with new drugs emerging and their efficacy gradually improving. Currently, the following chemotherapeutic drugs are commonly used in the treatment of breast cancer: cyclophosphamide (CTX), 5-fluorouracil (5-FU) and its derivatives, methotrexate (MTX), vincristine (NVB, Noviben, Gano), adriamycin (ADM), epi-amycin, cisplatin (DDP), carboplatin (CBP), paclitaxel (TAXOL) and polyene paclitaxel.