As we all know, the first choice for the treatment of breast cancer is surgery, but patients who have surgically removed the primary breast cancer nests and lymph nodes are not cured. In recent years, it has been thought that breast cancer is a systemic disease from the beginning. Even in the first stage cases without lymph node metastasis,10% ~16% still died of blood metastasis. Therefore, after radical resection of breast cancer, in order to further eliminate the tiny metastatic cancer foci that may exist in the body, it is necessary to implement an auxiliary treatment method of further treatment with anticancer drugs after surgery, which is called adjuvant chemotherapy in clinic, also known as escort chemotherapy. The effectiveness of breast cancer chemotherapy lies in the following two aspects.

(1)Gomptrtzian's law, after the main body of the tumor is surgically removed, the total load of cancer cells with residual cancer metastasis in the body is greatly reduced. At this time, the cancer cells in G0 stage return to the division and proliferation cycle, and the tumor doubling time is greatly shortened. This is a good time for chemotherapy drugs to play a killing role. Otherwise, if they develop to a certain extent, the proliferation ratio (Gf) of cancer cells will be reduced, which will delay the opportunity for chemotherapy drugs to play their role, so as soon as possible after the operation.

(2) Because the growth part (Gf) in cancer cells is inversely proportional to the total number of cancer cells, drugs insensitive to large tumors (with a small proportion of mitotic and proliferative cells) may be effective for smaller metastatic cancer foci (with a large proportion of mitotic and proliferative cells).