DISEASE CHARACTERISTICS:

• Histologically confirmed invasive breast cancer meeting the following criteria:

  • T1, T2, or operable T3 disease
  • Zero to three positive lymph nodes and no distant metastases

  • Unilateral tumor

    • Multifocal tumors are allowed provided that they have identical histology
    • Ductal carcinoma in situ or lobular carcinoma in situ allowed if invasive cancer is present

• Operable disease

  • Must have undergone breast-conserving surgery or mastectomy with either a sentinel node procedure or full axillary clearance

    • Radiotherapy is mandatory in the case of breast-conserving surgery
    • Unresectable positive deep margins and adjuvant radiotherapy with all other margins negative allowed

• Patients eligible for inclusion in the chemotherapy randomization must meet one of the following criteria:

  • High-risk of recurrence according to both the clinical-pathological criteria and the 70-gene signature
  • High risk of recurrence according to the clinical-pathological criteria and low-risk of recurrence according to the 70-gene signature and are randomized to use the clinical-pathological criteria for chemotherapy decision
  • Low-risk of recurrence according to the clinical-pathological criteria and high-risk of recurrence according to the 70-gene signature and are randomized to use the 70-gene signature for chemotherapy decision

• Patients eligible for inclusion in the endocrine therapy randomization must meet all of the following criteria:

  • Endocrine-responsive disease
  • Hormone receptor-positive disease (estrogen receptor-positive, progesterone receptor-positive, or both)

PATIENT CHARACTERISTICS:

• Female
• WHO performance status 0-1
• Neutrophil count > 1,500/mm^3
• Platelet count > 100,000/mm^3
• Creatinine clearance at least 50 mL/min OR creatinine up to 1.5 times upper limit of normal (ULN)
• ALT and AST up to 2.5 times ULN
• Alkaline phosphatase up to 2.5 times ULN
• Bilirubin up to 2.0 times ULN
• Normal echocardiogram (ECHO) compatible with chemotherapy treatment

• No serious cardiac illness or medical condition including, but not limited to, any of the following:

  • History of documented congestive heart failure
  • High-risk uncontrolled arrhythmias
  • Angina pectoris requiring antianginal medication
  • Clinically significant valvular heart disease
  • Evidence of transmural infarction on ECG
  • Poorly controlled hypertension (e.g., systolic blood pressure [BP] > 180 mm Hg or diastolic BP > 100 mm Hg)
  • Symptomatic coronary artery disease or a myocardial infarction within the past 12 months
  • Other risk factors that contraindicate the use of anthracycline-based chemotherapy
• No serious uncontrolled infection or other serious uncontrolled disease
• No other invasive cancer within the past 5 years except for adequately treated carcinoma in situ of the cervix or nonmelanoma skin cancer
• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective barrier contraception
• No psychological, familial, sociological, or geographical condition that would preclude study treatment
• No psychiatric disability
• No history of uncontrolled seizures or CNS disorders

• Patients eligible for inclusion in the chemotherapy randomization must meet all of the following additional criteria:

  • LVEF normal by ECHO or MUGA
  • No prior severe hypersensitivity reaction to drugs formulated with polysorbate 80
  • Must have physical integrity of the upper gastrointestinal tract
  • Able to swallow tablets
  • No malabsorption syndrome
• No prior thromboembolic disorder, deep vein thrombosis, or pulmonary emboli (for patients eligible for inclusion in the endocrine therapy randomization)

PRIOR CONCURRENT THERAPY:

• See Disease Characteristics
• No prior chemotherapy, hormonal therapy, or radiotherapy
• No participation in another investigational drug study within the past 4 weeks
• No systemic hormone replacement therapy (with or without progestins) for more than 3 months in duration

• Patients eligible for inclusion in the chemotherapy randomization must meet all of the following additional criteria:

  • Interval between definitive surgery and start of chemotherapy 6-12 weeks
  • No prior organ allografts requiring immunosuppressive therapy
  • No concurrent sorivudine or chemically related analogues, such as brivudine

• Patients eligible for inclusion in the endocrine therapy randomization must meet all of the following additional criteria:

  • No prior high-dose systemic corticosteroids (except as antiemetic treatment), immunotherapy, or biological response modifiers (e.g., interferon)
  • No prior adjuvant antiestrogen therapy for > 1 month immediately after surgery, radiotherapy, and/or chemotherapy
  • No hormone replacement therapy within the past 4 weeks
  • No antiestrogens as chemoprevention for breast cancer within the past 18 months
• No concurrent primary prophylaxis with filgrastim (G-CSF), sargramostim (GM-CSF), or pegfilgrastim

• No other concurrent treatment during endocrine therapy, including the following:

  • Anticancer therapy (anti-estrogens, aromatase inhibitors, chemotherapy)
  • Investigational agents
  • Raloxifene or other selective estrogen-receptor modulators

  • Hormonal contraceptives (including depot injections and implants)

    • Intrauterine devices, including progesterone-coated, allowed

  • Oral or transdermal hormonal treatments, including estrogen, progesterone, androgen, or aromatase inhibitor

    • Local vaginal (topical) estrogens with minimal systemic absorption allowed for severe vaginal dryness/dyspareunia
• Concurrent bisphosphonates allowed