Combined modality therapy has become the treatment of choice for patients with primary breast cancer, including those with locally advanced breast cancer. Primary or induction chemotherapy, followed by surgery or radiation therapy or both, and adjuvant systemic therapy is a generally accepted strategy. Most tumors respond with a more than 50% decrease in tumor size, and approximately 70% of patients experience down-staging through primary chemotherapy. Breast conservation is possible for many patients with locally advanced breast cancer, and almost all patients initially are rendered disease free. Primary chemotherapy should be the initial choice of treatment for patients with locally advanced tumors, but it is unclear what the optimal sequence of subsequent therapies should be, or whether one or two local treatment modalities are necessary. The most dramatic example of the efficacy of these regimens was demonstrated in patients with inflammatory breast cancer. Previously a universally fatal condition, the natural history of this disease has been changed dramatically by the introduction of these combined modality therapies. Five-year survival rates of 35-60% commonly are reported, and it is likely that about one third of patients with this highly aggressive form of disease will survive beyond 10 years without recurrence. Combined modality therapy that includes primary chemotherapy provides appropriate local control, the possibility of breast conservation therapy, and, probably, an increased survival rate, at least for some subsets of patients with locally advanced breast cancer. The use of similar treatment strategies for early breast cancer is currently under evaluation. Hormone therapy and combination chemotherapy represent the main treatment approaches to metastatic breast cancer. Radiotherapy is also a useful palliative tool, especially for control of painful bone metastases and central nervous system involvement. Patient and tumor characteristics help in the optimal selection of systemic therapy. Palliative therapy for symptomatic control and prolongation of life also preserves a good quality of life. Dose-intensive chemotherapy is being evaluated as a treatment to increase complete response rates and cause remission consolidation. Clinical trials on several new and effective cytotoxic agents, as well as new hormonal compounds, are being completed and are showing encouraging preliminary results.(ABSTRACT TRUNCATED AT 400 WORDS)