Chemotherapy for breast cancer is broadly classified into cases in which it is performed for the preoperative and postoperative prevention of metastasis and recurrence in order to save a patient's life, and cases in which it is performed to obtain an improvement in the QOL of metastatic cases in order to prolong the life of a patient. Preoperative and postoperative drug therapy tends to be oriented more toward aggressive since a permanent cure is difficult in metastatic cases, and it has been recommended that the drug therapy after a recurrence should begin with mild treatment so that the QOL will not be substantially impaired. There is no scientific basis regarding the extent to which the treatment of metastasis and recurrence should be performed. Basically, the treatment is sustained as long as it continues to be effective, but the treatment protocol is determined by consulting with patients and their family members while taking side effects and social factors into consideration as well. As to a characteristic of breast cancer, the peak age is about 50 years old, with metastatic and recurrent cases also involve many younger patients, so both the patients and their family members are less likely to abandon an aggressive treatment. Moreover, new effective drugs have been approved one after another to the extent that today from 30-40% of all patients are now able to survive for more than 5 years, even with distant metastases, which therefore reinforces the trend not to abandon an aggressive treatment.