PRIOR CONCURRENT THERAPY: Biologic therapy: No prior biologic therapy Chemotherapy: Prior or concurrent adjuvant chemotherapy allowed at investigator's discretion Recommended regimens: CMF (cyclophosphamide/methotrexate/fluorouracil) CEF (cyclophosphamide/etoposide/fluorouracil) AC (doxorubicin/cyclophosphamide) Choice of adjuvant chemotherapy regimen defined prior to randomization if given concurrently with protocol therapy Endocrine therapy: No estrogen, progestins, or androgen therapy for a period of more than 30 days following pathologic diagnosis of breast cancer Prior tamoxifen allowed All hormonal therapy discontinued prior to randomization Radiotherapy: See Disease Characteristics Surgery: See Disease Characteristics