DISEASE CHARACTERISTICS:

* Histologically confirmed noninvasive or small invasive breast cancer

* Low or intermediate grade (ductal carcinoma in situ, T1, or T2) OR
* Estrogen and/or progesterone receptor positive
* Largest mass no greater than 5 cm
* Clustered microcalcifications as only abnormality allowed with no upper size limit
* If no distinction between mass and microcalcifications, size as 1 lesion
* Lumpectomy or mastectomy must be planned for 2-6 weeks from start of study
* No evidence of metastases from any malignancy
* Hormone receptor status:

* Estrogen and progesterone receptor positive (unless low or intermediate grade tumor)

PATIENT CHARACTERISTICS:

Age:

* 18 and over

Sex:

* Female

Menopausal status:

* Postmenopausal by one of the following:

* Prior oophorectomy
* Over age 50 with prior hysterectomy, ovaries remaining
* Uterus and ovaries intact and no menstrual period for more than 3 months

Performance status:

* Not specified

Life expectancy:

* Not specified

Hematopoietic:

* Platelet count greater than 100,000/mm\^3
* Hemoglobin greater than 10 g/dL
* Absolute granulocyte count greater than 1,000/mm\^3

Hepatic:

* Albumin greater than 3 g/dL
* Bilirubin less than 1.5 mg/dL
* AST less than 100 U/L
* Alkaline phosphatase less than 200 U/L

Renal:

* Creatinine less than 1.5 mg/dL

Cardiovascular:

* No history of deep vein thrombosis

Pulmonary:

* No prior pulmonary embolus

Other:

* Not pregnant or nursing

PRIOR CONCURRENT THERAPY:

Biologic therapy:

* Not specified

Chemotherapy:

* At least 1 year since prior chemotherapy

Endocrine therapy:

* At least 1 year since prior aromatase inhibitors, antiestrogens, or LH agonists/antagonists
* No concurrent hormone replacement therapy or oral contraceptives (from time of randomization)

Radiotherapy:

* Not specified

Surgery:

* See Disease Characteristics

Other:

* No concurrent treatment for other malignancy