Toremifene With or Without Atamestane in Treating Postmenopausal Women With Metastatic Breast Cancer

DISEASE CHARACTERISTICS: Histologically confirmed metastatic breast cancer Bidimensionally measurable disease Lesion at least 2 cm in at least 1 diameter No failure with prior adjuvant antiestrogens within the first 12 months of treatment No progression of disease during therapy with prior aromatase inhibitors or selective estrogen receptor modulators (SERMs) (including SERMs for prevention of osteoporosis) No history of known central nervous system (CNS) metastases No bone metastases as only tumor manifestation Hormone receptor status: Estrogen receptor and/or progesterone receptor positive PATIENT CHARACTERISTICS: Age: 18 and over Sex: Female Menopausal status: Postmenopausal Performance status: ECOG 0-1 Life expectancy: At least 12 weeks Hematopoietic: Hemoglobin at least 9 g/dL Platelet count at least 100,000/mm3 WBC at least 2,000/mm3 Hepatic: AST and ALT no greater than 2.5 times upper limit of normal (ULN) Bilirubin no greater than 2.5 times ULN Renal: Creatinine no greater than 2.0 mg/dL Other: No significant neurological dysfunction including seizures or clinical signs of other significant neurological diseases No other active malignancy within the past 5 years except basal cell skin cancer or carcinoma in situ of the cervix No contraindication to toremifene or its excipients or any of the excipients in atamestane Not pregnant or nursing PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: No prior cytotoxic chemotherapy for metastatic disease At least 6 months since prior adjuvant chemotherapy No concurrent chemotherapy Endocrine therapy: See Disease Characteristics No prior hormonal therapy for metastatic disease At least 12 months since prior adjuvant antiestrogens No concurrent SERMs or estrogenic or androgenic hormones No other concurrent aromatase inhibitors Radiotherapy: No concurrent radiotherapy except for palliation for bone metastases Surgery: Not specified Other: No prior enrollment in this study At least 30 days since prior investigational drugs No other concurrent investigational drugs Concurrent bisphosphonates for bone metastases allowed