Hormone Therapy in Treating Postmenopausal Women With Receptor-Positive Breast Cancer

DISEASE CHARACTERISTICS: Histologically confirmed adenocarcinoma of the breast Pathologic stage T1-3, N1-2, M0 No clinical or pathologic T4 disease No primary tumor fixed to chest wall No axillary nodes fixed to chest wall or neurovascular bundle No preoperative arm edema No clinical skin involvement (microscopic focal dermal invasion or dermal lymphatic involvement eligible) No clinical N2 disease Modified radical mastectomy or lumpectomy required prior to entry Sentinel node biopsy allowed Randomization required within 12 weeks from definitive surgery Surgery dated from mastectomy or axillary dissection for lumpectomy No positive deep mastectomy margins Radiotherapy planned within 12 weeks following axillary node dissection for lumpectomy patients Synchronous bilateral breast cancer eligible If tumor is at least 2 cm, then nodes not involved If no tumor is at least 2 cm, then at least 1 node must be involved Both invasive primaries receptor-positive Previously treated, noninvasive breast cancer eligible No prior invasive breast cancer No adenoid cystic, squamous, or sarcomatous histology Hormone receptor status: Estrogen- or progesterone-receptor positive, i.e.: At least 10 fmole/mg cytosol protein by ligand-binding assay OR Receptor positive by immunocytochemistry PATIENT CHARACTERISTICS: Age: 65 and over OR Postmenopausal and ineligible/inappropriate for or declined other active node positive adjuvant studies Sex: Female Menopausal status: Postmenopausal, defined as: At least 1 year since last menstrual period Hysterectomized with bilateral oophorectomy Hysterectomized with 1 or both ovaries remaining and either: Over 60 FSH in postmenopausal range Not surgically castrated, under 60, and on HRT FSH elevated 2 weeks after HRT discontinued Performance status: Not specified Life expectancy: At least 7 years except for breast cancer Hematopoietic: WBC greater than 3,000/mm3 Platelet count at least 100,000/mm3 Hemoglobin at least 10 g/dL Hepatic: Bilirubin no greater than 1.5 mg/dL AST less than 2 times normal Renal: Creatinine no greater than 2.0 mg/dL BUN no greater than 25.0 mg/dL Other: No extensive macular degeneration on exam within 1 year of entry, e.g.: No exudative or atrophic macular lesions that reduce corrected vision to less than 20/40 Health adequate for protocol treatment No nutritional supplementation except single daily multivitamin No other vitamin A supplements Gynecologic exam within the past year required of women who retain a uterus No second malignancy within the past 10 years except: Inactive nonmelanomatous skin cancer Carcinoma in situ of the cervix Prior noninvasive contralateral breast cancer PRIOR CONCURRENT THERAPY: No prior chemotherapy or hormonal therapy for breast cancer except: Up to 1 month of tamoxifen if started by a non participating physician At least 2 weeks since hormone replacement therapy No concurrent megestrol