DISEASE CHARACTERISTICS: Histologically proven, invasive, localized carcinoma of the breast Stage I/II/IIIA disease, i.e.: Tumor confined to breast on clinical examination Overlying skin movable with respect to tumor Tumor movable in relation to underlying muscle and chest wall Bone scan and/or x-ray required to rule out bone metastases in cases of skeletal pain Tumor size requirements: No greater than 5 cm if lymph nodes are positive Greater than 1 cm if lymph nodes are negative Tumor definitively treated by one of the following procedures: Total mastectomy with axillary node dissection Segmental mastectomy with or without axillary node dissection and/or sentinel node biopsy followed by breast irradiation, provided: Surgical margins are histologically free of invasive or noninvasive tumor One additional resection allowed to obtain clear margins Total mastectomy required if clear margins are not obtained at second resection The following conditions exclude: Bilateral malignancy or any mass in the contralateral breast unless proven nonmalignant by biopsy Palpable lymph nodes in the contralateral axilla or probable supraclavicular or infraclavicular nodal involvement unless proven nonmalignant by biopsy 10 or more positive lymph nodes Inflammatory breast cancer Ulceration or erythema Infiltration of the skin or peau d'orange Tethering or dimpling of the skin or nipple inversion should not be considered skin infiltration Satellite breast nodules Parasternal nodules Edema of the arm Hormone receptor status: Any estrogen receptor (ER) or progesterone receptor (PR) status allowed ER assessment required PR assessment recommended Less than 365 days between definitive surgery and randomization