DISEASE CHARACTERISTICS:

• Histologically proven invasive adenocarcinoma of the breast

  • Stage I or II (T1-3, N0-1, M0)

• Must have undergone total mastectomy OR lumpectomy with an axillary dissection or sentinel node biopsy

  • If any sentinel node is proven histologically positive by hematoxylin-eosin stain (H&E) or deemed suspicious by H&E and confirmed positive by immunohistochemistry, axillary dissection is required
• No bilateral malignancy or mammographically suspicious mass or abnormality within the contralateral breast unless histologically benign

• Lumpectomy patients eligible if the following conditions are met:

  • Tumor less than 5 cm (tumor 5 cm or greater allowed at discretion of protocol investigator)

  • Margins of resected specimen must be histologically free of invasive tumor and ductal carcinoma in situ

    • Additional surgical resections to obtain clear margins allowed even if axillary dissection has been performed
    • If residual tumor at resected margins after re-excision(s), total mastectomy is required
  • No diffuse tumors by mammography that would not be considered surgically amenable to lumpectomy
  • No other clinically dominant mass or mammographically suspicious abnormality within the ipsilateral breast remnant unless histologically benign or, if malignant, surgically removed with clear margins

• No ulceration, erythema, infiltration of the skin or underlying chest wall (complete fixation), peau d'orange, or skin edema of any magnitude

  • Tethering or dimpling of skin or nipple inversion allowed and not considered skin infiltration
• No ipsilateral lymph nodes fixed to one another or to other structures (cN2 disease) by clinical examination
• No suspicious palpable nodes in the contralateral axilla or palpable supraclavicular or infraclavicular nodes, unless biopsy evidence of no tumor involvement
• No significant nonmalignant bone disease that is likely to interfere with interpretation of bone x-rays

• Skeletal pain allowed only if bone scan and/or roentgenological examination fails to disclose metastatic disease

  • Suspicious findings must be confirmed as benign by x-ray, MRI, or biopsy
• No prior breast cancer except lobular carcinoma in situ

• Hormone receptor status:

  • Must have an analysis of estrogen receptor (ER) and progesterone receptor (PR) status on the primary tumor before randomization

PATIENT CHARACTERISTICS:

Age:

• Not specified

Sex:

• Female

Menopausal status:

• Not specified

Performance status:

• Zubrod 0-2

Life expectancy:

• At least 10 years (excluding diagnosis of breast cancer)

Hematopoietic:

• Absolute neutrophil count at least 1,500/mm^3 (unless due to ethnic or racial variation)
• Platelet count at least 100,000/mm^3

Hepatic:

• No hepatic disease that would preclude study entry
• Bilirubin no greater than upper limit of normal (ULN)
• Alkaline phosphatase less than 2.5 times ULN
• SGOT less than 1.5 times ULN
• Albumin normal

Renal:

• No renal disease that would preclude study entry
• Creatinine normal
• Calcium normal

Cardiovascular:

• No cardiovascular disease that would preclude study entry

Other:

• No nonmalignant systemic disease that would preclude study entry
• No psychiatric or addictive disorders that would preclude informed consent
• Not pregnant or nursing
• Fertile patients must use effective contraception

• No other prior malignancy within the past 5 years except:

  • Effectively treated squamous cell or basal cell skin cancer
  • Carcinoma in situ of the cervix treated by surgery only
  • Lobular carcinoma in situ of the ipsilateral or contralateral breast treated by hormonal therapy and/or surgery
  • Patients with other malignancy who have been disease free for at least 5 years and are at low risk of recurrence

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• No prior biologic therapy for breast cancer

Chemotherapy:

• No prior chemotherapy for breast cancer
• Concurrent chemotherapy allowed at the discretion of the protocol investigator

Endocrine therapy:

• No prior hormonal therapy for breast cancer except adjuvant tamoxifen initiated within 4 weeks prior to study
• No concurrent sex hormonal therapy (e.g., birth control pills or ovarian hormone replacement therapy)
• No concurrent calcitonin

• No other concurrent hormonal agents for the management of menopausal symptoms until time of first breast cancer recurrence or development of second primary cancer except:

  • Low-dose estrogen vaginal creams or conjugated estrogen ring (Estring) for symptomatic vaginal dryness
  • Raloxifene or other selective estrogen receptor modulators for prevention of osteoporosis
  • Adjuvant luteinizing hormone-releasing hormone agonists/antagonists for medical ovarian ablation
• No concurrent tamoxifen during study chemotherapy

Radiotherapy:

• No prior radiotherapy for breast cancer
• No other concurrent radiotherapy, including regional node radiotherapy, for patients with node-negative breast cancer

Surgery:

• See Disease Characteristics
• No more than 84 days since last surgery (lumpectomy, mastectomy, sentinel node biopsy, axillary dissection, or re-excision of lumpectomy margins) for breast cancer

Other:

• No concurrent participation in any other clinical trials of systemic therapy for early stage breast cancer except for the following radiotherapy trials:

  • NCIC-MA.20 for node-positive patients
  • SWOG-S9927 for node-positive mastectomy patients
• No concurrent alendronate or other bisphosphonates (e.g., pamidronate) until time of osseous metastasis
• No concurrent calcitonin for treatment or prevention of osteoporosis