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

PURPOSE: Randomized phase III trial to compare the effectiveness of two combination chemotherapy regimens in treating women with breast cancer who have undergone surgery to remove the tumor.

OBJECTIVES: I. Determine whether doxorubicin/docetaxel (DD) will improve disease-free survival and overall survival when compared to doxorubicin/cyclophosphamide (DC) in women with lymph node positive (1-3 positive nodes) or high risk lymph node negative breast cancer. II. Compare the toxicity of DD to DC in this patient population.

OUTLINE: This is a randomized study. Patients are stratified by node status (positive vs negative), menopause status (pre- vs post), estrogen receptor (ER) status/progesterone receptor (PR) status (ER/PR unknown vs ER+/PR+ vs ER+/PR- vs ER-/PR+ vs ER-/PR-). Patients in arm I receive doxorubicin IV plus docetaxel IV over 1 hour every 3 weeks for 4 treatment courses. Patients in arm II receive doxorubicin IV plus cyclophosphamide IV every 3 weeks for 4 treatment courses. All patients who are estrogen receptor or progesterone receptor positive receive oral tamoxifen daily for 5 years following chemotherapy. Some patients may also receive radiotherapy following chemotherapy. Patients are followed every 3 months if patient is less than 2 years from study entry; every 6 months if patient is 2-5 years from study entry; and every 12 months if patient is greater than 5 years from study entry.

PROJECTED ACCRUAL: Approximately 2778 patients will be accrued for this study within 2.5 years.

DISEASE CHARACTERISTICS: Histologically confirmed resectable adenocarcinoma of the breast Histologically positive lymph nodes (1 to 3) OR Lymph node negative and high risk disease Tumor greater than 1.0 cm diameter May have undergone an axillary dissection with at least 6 nodes removed and examined or a sentinel node biopsy Patients who are positive by sentinel node biopsy will receive an axillary dissection No locally advanced or inflammatory or metastatic breast cancer Hormone receptor status: Not specified

PATIENT CHARACTERISTICS: Age: 18 and over Sex: Female Menopausal status: Not specified Performance status: Not specified Life expectancy: Not specified Hematopoietic: Neutrophil count at least 1,500/mm3 Platelet count at least 100,000/mm3 Hepatic: Adequate hepatic function Bilirubin no greater than upper limit of normal Renal: Adequate renal function Cardiovascular: Adequate cardiac function Normal MUGA or echocardiogram Other: Not pregnant or nursing Fertile patients must use effective barrier method contraception At least 5 years since prior invasive malignancies, except basal cell or squamous cell carcinoma of the skin or carcinoma in situ of the cervix

PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: No prior chemotherapy for this malignancy Endocrine therapy: No concurrent tamoxifen Up to 4 weeks of tamoxifen treatment for this malignancy allowed Radiotherapy: No prior radiotherapy for this malignancy Prior radiotherapy to the breast for ductal carcinoma in situ allowed Surgery: Tumor should be removed by either a modified radical mastectomy and/or a segmental mastectomy plus axillary lymph node dissection or sentinel node biopsy before beginning treatment on protocol No greater than 84 days since last surgical procedure that constitutes or completes definitive surgical therapy (mastectomy; axillary dissection/sentinel node biopsy; or resection of primary site to obtain a negative margin