Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically confirmed invasive breast carcinoma

- Primary operable breast cancer that was surgically treated by wide local excision or
mastectomy with clear margins (> 1 mm apart from deep margin if full thickness
resection)

- No more than 8 weeks since prior definitive surgery

- Early-stage disease with no evidence of metastases clinically or on routine staging
investigations

- No T4 and/or N3 disease

- Prior axillary staging required, including 1 of the following:

- Sentinel node biopsy

- Axillary sampling or clearance

- All node-positive patients must have had axillary clearance or radiotherapy
to the axilla

- Must be at high risk of relapse within 5 years (risk factors evaluated at clinician's
discretion)

- No other invasive breast cancer, systemically treated ductal carcinoma in situ
(DCIS), or solid tumor within the past 5 years

- No prior hematologic malignancy or melanoma

- Hormone receptor status:

- Estrogen receptor (ER)- or progesterone receptor (PR)-negative OR ER/PR-weakly
positive (e.g., Allred/Quick score ≤ 5 OR H score ≤ 100)

PATIENT CHARACTERISTICS:

- Female

- Postmenopausal

- Performance status 0-1

- Hemoglobin > 9 g/dL

- WBC > 3,000/mm³

- Platelet count > 100,000/mm³

- Bilirubin normal (unless known Gilbert's disease is present)

- Albumin normal

- AST and ALT ≤ 1.5 x upper limit of normal (ULN)

- Creatinine ≤ 1.5 x ULN

- Creatinine clearance > 50 mL/min

- No active or uncontrolled infection

- Must be available for routine long-term hospital follow-up

- Must have normal cardiac function and no significant cardiac disease by ECHO or MUGA

PRIOR CONCURRENT THERAPY:

- See Disease Characteristics

- At least 4 weeks since prior preoperative endocrine therapy

- No prior systemic therapy for this breast cancer or mantle radiotherapy

- No prior breast-conserving surgery in which there is a contraindication for, or
decline of postoperative radiotherapy

- No concurrent hormone replacement therapy (HRT)