 The search for prognostic and predictive factors that could influence the survival of patients treated for metastatic breast cancer has already been the subject of several studies. It seems that 2 components in the natural outcome of tumors must be considered. The first category is related to the primary characteristics such as initial histological grade, hormonal receptor status. The second category is linked to the metastatic characteristics: proliferation index reflected by the length of disease-free interval, type and number of metastatic sites involved. On the other hand, some prognostic factors are linked to the treatments undertaken, stressing their impact on the natural outcome of the disease: type of hormonotherapy, type of chemotherapy, type of response achieved by treatment. 