 RATIONALE: Drugs used in chemotherapy, such as cyclophosphamide, methotrexate, fluorouracil, and epirubicin hydrochloride, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. It is not yet known whether giving cyclophosphamide together with methotrexate and fluorouracil before, after, or without epirubicin hydrochloride is more effective in treating patients with breast cancer that can be removed by surgery. 