DISEASE CHARACTERISTICS: Diagnosis of metastatic breast cancer Prior tamoxifen therapy failure within 1 year of study defined as follows: Prior tamoxifen therapy for metastatic disease with prior response and progression of disease while still on treatment or within 1 year of last treatment Prior adjuvant tamoxifen therapy for a minimum of 2 years with subsequent progression of disease while still on treatment or within 1 year of last treatment Postmenopausal Must be amenorrheic for at least 12 months Removal of both ovaries or chemotherapy induced menopause allowed At least 1 bideminsionally measurable lesion No disease restricted only to bone No symptomatic CNS metastases untreated by surgery or radiotherapy Hormone receptor status: Estrogen or progesterone receptor positive