Combination Chemotherapy in Treating Patients With Early Stage Breast Cancer That Has Been Removed By Surgery

DISEASE CHARACTERISTICS: * Histological diagnosis of invasive breast carcinoma * Cytological proof of malignancy alone is not sufficient * Early stage disease (T0-3, N0-2, M0) without clinical suspicion or evidence of distant metastases on routine staging * No locally advanced breast cancer (T4 and/or N3 disease) * Completely resected disease by breast-conserving surgery with axillary node clearance or modified radical mastectomy within the past 4-8 weeks * Negative surgical margins required, unless either of the following are true: * Deep surgical margins after full thickness resection * Noninvasive cancer at surgical margins for which a mastectomy is planned after completion of study chemotherapy * No contraindication for or refusal of postoperative radiotherapy in patients who underwent prior breast-conserving surgery * Definite indication for adjuvant chemotherapy * No prior or current invasive breast cancer or bilateral breast cancer * Prior surgically-treated ductal carcinoma in situ or lobular carcinoma in situ allowed * Hormone receptor status: * Estrogen receptor- and/or progesterone receptor-positive or -negative tumor PATIENT CHARACTERISTICS: * Sex: male or female * Menopausal status: premenopausal or postmenopausal * No previous malignancy except basal cell carcinoma, carcinoma in situ of the cervix, or any cancer from which the patient has been disease-free for 10 years and for which treatment consisted solely of resection * ECOG status 0 or 1 * Hemoglobin \> 9 g/dL * WBC \> 3,000/mm³ * Platelet count \> 10,000/mm³ * Bilirubin normal (unless due to known Gilbert's disease) * AST and ALT ≤ 1.5 times upper limit of normal (ULN) * Albumin normal * Creatinine ≤ 1.5 times ULN * Creatinine clearance \> 50 mL/min * No active, uncontrolled infection * Not pregnant or nursing * Fertile patients must use effective contraception * No concurrent medical, psychiatric, or geographic problems that might prevent completion of treatment or follow-up * Available for a minimum of 5 years' follow-up * No known serious viral infection such as active hepatitis B, hepatitis C, or HIV * No significant cardiac disease, such as impaired left ventricular function or active angina requiring regular anti-anginal medication and/or resulting in restricted physical activity * No history of significant renal impairment or disease PRIOR CONCURRENT THERAPY: * No simultaneous participation in the active intervention phase of another treatment trial * Not being approached or recruited for another trial within 2 months of study entry * No previous chemotherapy, hormonal therapy or radiotherapy for the treatment of pre-invasive or invasive cancer except for either of the following: * Previous radiotherapy for basal cell carcinoma * Previous preoperative endocrine therapy, provided there was no evidence of progression during this therapy, it lasted for less than 6 weeks in duration, and it was stopped at least one month prior to trial entry * Concurrent luteinizing hormone-releasing hormone analog therapy allowed for premenopausal patients * More than 4 weeks since prior hormone replacement therapy (HRT) or pre-operative endocrine therapy * No prior breast conserving surgery if there is a contradiction for or refusal of postoperative radiotherapy