Single-Photon Emission Computed Tomography, Computed Tomography Lymphoscintigraphy, and Intensity-Modulated Radiation Therapy in Treating Patients Who Have Undergone Surgery for Stage I or Stage II Breast Cancer

DISEASE CHARACTERISTICS: * Biopsy-proven primary invasive breast cancer, meeting one of the following criteria: * Stage I or II disease with negative sentinel or axillary node dissections * Stage II disease with micrometastases (defined as \< 2.0 mm focus) in 1-2 lymph nodes and/or a single positive axillary node ≤ 1 cm with no extracapsular extension * Completed all surgical intervention (e.g., lumpectomy, mastectomy) * Planning adjuvant whole breast irradiation including the low axilla * No bilateral or recurrent breast cancer PATIENT CHARACTERISTICS: * ECOG performance status 0-2 * Not pregnancy or nursing * Negative pregnancy test * Able to complete questionnaire(s) alone or with assistance * No active infection * No history of invasive cancer within the past 5 years, except basal cell or squamous cell skin cancers PRIOR CONCURRENT THERAPY: * See Disease Characteristics * No prior surgery or radiation to the ipsilateral breast or axilla * No concurrent neoadjuvant chemotherapy or radiotherapy