RATIONALE: Drugs used in chemotherapy, such as epirubicin, cyclophosphamide, paclitaxel, and fluorouracil, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Giving more than one drug (combination chemotherapy) may kill more tumor cells. Colony-stimulating factors, such as pegfilgrastim, may increase the number of immune cells found in bone marrow or peripheral blood and may help the immune system recover from the side effects of chemotherapy. Giving combination chemotherapy and pegfilgrastim after surgery may kill any tumor cells that remain after surgery. It is not yet known whether combination chemotherapy is more effective with or without fluorouracil and/or pegfilgrastim in treating breast cancer.