The anticancer agent paclitaxel (marketed as Taxol) has shown remarkable activity against metastatic breast cancer. However, the Taxol formulation requires prolonged administration times, and there are safety problems that have been attributed to the solvent rather than the active ingredient, paclitaxel. This is a new formulation of paclitaxel that has been found to have fewer safety problems than Taxol, and may be administered safely at higher doses. This study will investigate the safety and efficacy of this new formulation of paclitaxel given intravenously once a week for three weeks, followed by a rest week. This cycle will be repeated until safety problems or treatment failure require that the patient stop therapy.