The data reviewed in this conference suggest that initial therapeutic decisions for patients with metastic breast cancer be based on the presence or absence of an estrogen receptor in the tumor. Patients with estrogen receptor in their original primary breast cancer or in a subsequent metastitic lesion are candidates for hormonal manipulation, whereas patients lacking estrogen receptor in their tumor are treated for their metastic disease with nonhormonal chemotherapy. Nonhormonal therapy usually consists of a combination of cytotoxic drugs including cyclophosphamide, methotrexate, and 5-fluorouracil (CMF). Other programs of combination chemotherapy are under active study, especially programs that include nonspecific immune stimulation with Corynebacterium parvum or bacillus Calmette-Guérin (BCG). Inasmuch as patients with Stage II primary breast cancer frequently have "micrometastatic" disease, combination chemotherapy is also under study as an adjuvant to surgery. Preliminary results strongly support the use of such therapy.