PATIENT CHARACTERISTICS: Age: Postmenopausal Sex: Women only Menopausal status: Postmenopausal by one or more of the following: Amenorrhea lasting more than 1 year in women under 50 years of age with no prior hysterectomy No menses for 6 months prior to breast surgery in women 50 years of age and over with no prior hysterectomy Documented oophorectomy prior to breast cancer diagnosis Luteinizing hormone and follicle-stimulating hormone values diagnostic of postmenopausal status by local laboratory criteria Women 50 years of age and over with prior hysterectomy Performance status: ECOG 0-2 Life expectancy: At least 5 years Hematopoietic: WBC at least 3,000/mm3 Platelet count at least 100,000/mm3 Hepatic: (unless metastatic disease ruled out by radiologic exam) AST or ALT less than twice normal Alkaline phosphatase less than twice normal Renal: Not specified Other: No symptomatic gallbladder disease or cholecystitis No intercurrent illness that reduces life expectancy to less than 5 years No other major medical or psychiatric illness that precludes study treatment or follow-up No second malignancy within 5 years except: Adequately treated basal cell skin carcinoma Adequately treated cancer of the cervix, endometrium, colon, or thyroid Able and willing to complete quality-of-life questionnaires in English or French Illiteracy, loss of sight, or other inability to complete questionnaires does not exclude Accessible for treatment and follow-up