RATIONALE: Drugs used in chemotherapy use different ways to stop tumor cells from dividing so they stop growing or die. It is not yet known which combination chemotherapy regimen is more effective following surgery for breast cancer.

PURPOSE: Randomized phase III trial to study the effectiveness of combination chemotherapy consisting of cyclophosphamide, methotrexate, and fluorouracil with or without epirubicin in treating women who have early stage breast cancer.

OBJECTIVES: I. Compare the effects of 4 courses of epirubicin followed by 4 courses of cyclophosphamide/methotrexate/fluorouracil (CMF) versus 8 courses of CMF as adjuvant chemotherapy in women with node positive early breast cancer, as measured by overall and event free survival from the date or randomization. II. Compare the effects of 4 courses of epirubicin followed by 4 courses of CMF with 8 courses of CMF as adjuvant chemotherapy in these patients, as measured by acute and chronic toxicities. III. Compare the effects of 4 courses of epirubicin followed by 4 courses of CMF versus 8 courses of CMF as adjuvant chemotherapy in these patients, as measured by quality of life.

OUTLINE: This is a randomized, multicenter study. Patients are randomized into 2 treatment arms within 4 weeks of surgery. Treatment begins within 6 weeks of surgery. One treatment arm receives 8 courses of cyclophosphamide/methotrexate/fluorouracil (CMF) given intravenously (IV) every 3 weeks. The other arm receives 4 courses of epirubicin followed by 4 courses of CMF given IV every 3 weeks. Patients are followed annually for 10 years.

PROJECTED ACCRUAL: A total of 1,000 patients will be accrued over 3 years.

DISEASE CHARACTERISTICS: Histologically confirmed, early stage, unilateral invasive breast cancer of TNM stages T0 - T3, N0-1, M0, i.e., Histologically proven axillary node metastases OR Lymph node negative Not locally advanced If supraclavicular node is enlarged or suspicious of metastasis, negative biopsy for supraclavicular node metastases required No evidence of any other metastases clinically or on routine staging investigations No past history of pure in situ carcinoma in either breast Primary tumor is completely excised

PATIENT CHARACTERISTICS: Age: Not specified Sex: Female Performance status: Not specified Hematopoietic: Neutrophil count greater than 2,000/mm3 Platelet count greater than 100,000/mm3 No evidence of sepsis Hepatic: Adequate hepatic function Bilirubin normal AST/ALT normal Renal: Adequate renal function Creatinine less than 1.2 mg/dL Cardiovascular: No clinically significant cardiovascular disease Other: No prior or concurrent other malignancy except adequately treated basal or squamous cell carcinoma of the skin or in situ carcinoma of the cervix Not pregnant or nursing Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: No prior chemotherapy Endocrine therapy: Prior tamoxifen allowed Radiotherapy: No prior radiotherapy Surgery: See Disease Characteristics