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