Patient description: The patient is a 42 year-old postmenopausal woman who had a screening sonogram which revealed an abnormality in the right breast. She had no palpable masses on breast exam. Core biopsy was done and revealed a 1.8 cm infiltrating ductal breast carcinoma in the left upper outer quadrant. Lumpectomy was done and the surgical margins were clear. The tumor was HER2-positive and ER/PR negative. Axillary sampling revealed 1 positive lymph node out of 12 sampled. CXR was unremarkable. She is using “well women” multivitamins daily and no other medication. She smokes frequently and consumes alcohol occasionally. She is in a relation with only one partner and has a history of 3 pregnancies and live births. She breastfed all three children.

Clinical trial eligibility criteria: eligible ages (years): 18.0-999.0,  Breast Cancer Histologically proven adenocarcinoma of the breast No apocrine, adenoidcystic, or squamous carcinomas or sarcomas Pathologic Stage T1-3a, pathologic N1-2 (clinical N0-1), M0: Rendered free of gross tumor at surgery Primary tumor movable with respect to chest wall Axillary nodes movable with respect to chest wall and each other No preoperative edema of the arm, peau d'orange, skin ulceration, or inflammatory lesions One or more positive lymph nodes required No positive deep mastectomy margins or clinical skin involvement (focal microscopic dermal invasion or focal microscopic dermal lymphatic involvement allowed) No evidence of metastatic disease on pretherapy studies (including chest x-ray, bone scan, and mammogram) No bilateral invasive tumors Patients who had noninvasive ductal carcinoma in situ of the opposite breast and underwent prophylactic contralateral mastectomy are eligible Hormone receptor status: Positive for estrogen and/or progesterone receptors (at least 10 fmol/mg protein or unequivocally positive immunocytochemical assay for one or both) Participation in SWOG-8854 (flow cytometry) recommended Age: Any age Sex: Females only Menopausal status: Postmenopausal as defined by 1 or more of the following: Bilateral oophorectomy at least 2 months prior to diagnosis of breast cancer (with or without estrogen therapy following surgery) Prior hysterectomy with at least 1 ovary remaining and either over 60 years old or with a postmenopausal FSH level Natural menopause (last menstrual period at least 1 year prior to registration or 4-12 months prior to registration with a postmenopausal FSH level) Treated with postmenopausal estrogen therapy and either over 55 years old or with a postmenopausal FSH level Performance status: Not specified Hematopoietic: WBC at least 3,500/mm3 Platelet count at least 100,000/mm3 Hepatic: Bilirubin no more than 1.2 x normal Alkaline phosphatase no more than 1.2 x normal SGOT or SGPT no more than 1.2 x normal Renal: Creatinine no more than 2.0 mg/dL Cardiovascular: No uncontrolled hypertension No history of ischemic heart disease or CHF Normal ejection fraction by MUGA (required only if deemed clinically necessary for assessment) Other: No medical condition that would preclude protocol therapy: No severe diabetes No active ulcer disease No significant psychiatric disease No second malignancy within 5 years except: Adequately treated nonmelanomatous skin cancer Curatively treated Stage I cervical carcinoma Pretreatment mammogram and chest x-ray completed no more than 3 months preoperatively; blood/body fluid analyses to determine completed within 14 days prior to registration; prestudy bone scan completed within 12 weeks prior to registration and/or within 4 weeks prior to surgery PRIOR Biologic therapy: Not specified Chemotherapy: No prior chemotherapy Endocrine therapy: No prior hormonal therapy (except for up to 14 days of tamoxifen stopped prior to registration) Prior estrogen and/or progesterone-containing hormone preparations for nononcologic therapy allowed, but must be discontinued prior to registration Postmenopausal estrogen therapy should be discontinued in all patients at the time of diagnosis of breast cancer Radiotherapy: Postoperative chest wall and/or regional lymph node irradiation allowed for mastectomy patients (at discretion of the physician) either prior to registration or on protocol for any of the following: Tumor greater than 5 cm in diameter 4 or more positive nodes Extranodal extension of tumor into the axillary fat No radiotherapy for any other reason in mastectomy patients Postoperative radiotherapy either prior to registration, during tamoxifen, or after completion of chemotherapy required for lumpectomy patients Radiotherapy must be completed (if it is to be given before chemotherapy) prior to registration No immediate radiotherapy after randomization to chemotherapy Surgery: Radical, modified radical, or breast-sparing surgical procedure with at least a level I and II axillary dissection and analysis of at least 6 nodes required within 12 weeks prior to registration Lumpectomy must Total excisional biopsy with rim of normal breast tissue Microscopically negative margins Level I and II axillary dissection Tumor no more than 5 cm in greatest diameter Clinical and mammographic examination demonstrating absence of multicentric lesions Type of surgery, number of nodes examined, number of positive nodes, and size of the primary tumor (size of the largest tumor if more than 1 mass) must be recorded