Patients with metastatic breast cancer consist of a heterogeneous group of patients whose prognoses and clinical courses can vary depending on host factors, such as comorbidity and age, and on tumor factors, such as hormone-receptor status, grade, and anatomical site of disease. Although the median survival time for patients with metastatic breast cancer is 2-4 years, subsets of patients with either indolent or limited metastatic disease may have prolonged survival times. Further, expectations of treatment, both in terms of efficacy and of toxicity, vary greatly based upon the specific treatment, patient characteristics, and tumor characteristics. Thus, the goals of treatment for patients with metastatic breast cancer are influenced by estimates of prognoses as well as a balance between physician and patient preferences regarding efficacy and toxicity considerations. Traditionally, objective measures of response and survival have been the targeted end points in clinical trial design and in physician selection of therapy for metastatic breast cancer. More recently, issues of quality of life have surfaced as important end points, especially from the perspective of the patient. The decision-making process in selecting the optimal treatment for patients with metastatic breast cancer is, therefore, a multidimensional process involving subjective as well as objective goals of treatment. Ultimately, the benefits of treatment must justify the risks and toxicities of the treatment, and the impact of treatment should be measured in relation to specified goals. Both physician and patient perspectives are important in establishing the objectives of treatment, and this process is optimally an interactive and ongoing process throughout the course of disease.