OUTLINE: This is a randomized, multicenter study. Patients are stratified by the number of positive axillary nodes (4-9 vs at least 10) and by center. Patients are randomized to one of two treatment arms. Arm I: Patients receive induction therapy consisting of doxorubicin IV every 3 weeks for 4 courses followed by consolidation therapy consisting of cyclophosphamide IV, methotrexate IV, and fluorouracil IV every 3 weeks for 8 courses. At week 4 of consolidation therapy, patients receive radiotherapy to the breast, chest wall, and axilla over 3-5 weeks or as appropriate. Following recovery from consolidation therapy, patients receive maintenance therapy consisting of oral tamoxifen daily for 5 years. Arm II: Patients receive induction therapy as in arm I followed by consolidation therapy consisting of stem cell mobilization with high dose cyclophosphamide IV over 2 hours and filgrastim (G-CSF) subcutaneously beginning 24 hours after cyclophosphamide and continuing until blood counts recover. At 13-28 days following peripheral blood stem cell (PBSC) collection and/or autologous bone marrow collection, patients undergo chemoablation consisting of thiotepa IV and cyclophosphamide IV continuously over 4 days followed 72 hours later by PBSC infusion with or without autologous bone marrow. Following hematologic recovery, patients receive radiotherapy and maintenance therapy as in arm I. Patients are followed every 6 months for 2 years, then annually.