The harm of stopping chemotherapy for breast cancer is mainly to affect the treatment, because chemotherapy is mainly to treat and control the proliferation of cancer cells, and if it is stopped suddenly, it may cause the cancer cells to continue to develop, spread to the whole body, and even jeopardize the life of the patient. If chemotherapy for breast cancer is stopped in the middle, the cancer cells will not be inhibited, and the spread of cancer cells may invade the lymphatic system and blood system, which will change the patient’s condition, and if the breast cancer is in the middle stage, it is likely to be progressed to the advanced stage, which will affect the quality of the patient’s survival and the time limit of his/her life. Breast cancer chemotherapy is not recommended to be stopped in the middle of the course, and the appropriate chemotherapy cycle should be chosen under the guidance of doctors. However, some patients have to stop chemotherapy due to excessive reaction to chemotherapy drugs, such as severe gastrointestinal reaction or bone marrow toxicity, then chemotherapy intervals can be carried out under the guidance of doctors, and then the next stage of chemotherapy can be carried out after evaluation. Breast cancer chemotherapy is not recommended to be stopped in the middle of the treatment, and it should be carried out reasonably under the guidance of doctors.