Radiation Therapy in Women With Low Risk Early-Stage Breast Cancer Who Have Undergone Breast Conservation Surgery

OBJECTIVES: * To test partial breast radiotherapy using intensity-modulated techniques following complete local tumor excision in women with low-risk, early stage breast cancer. OUTLINE: This is a multicenter study. Patients are stratified according to center (not participating in sub-studies vs participating in sub-studies). Patients are randomized to 1 of 3 treatment arms. * Arm I (control): Patients undergo standard whole breast radiotherapy once daily on days 1-5 (15 fractions) for 3 weeks. * Arm II: Patients undergo reduced whole breast radiotherapy (15 fractions) and standard partial breast radiotherapy (15 fractions) once daily on days 1-5 for 3 weeks. * Arm III: Patients undergo standard partial breast radiotherapy once daily on days 1-5 (15 fractions) for 3 weeks. All patients complete a family history questionnaire at baseline. Patients also undergo blood sample collection at baseline and paraffin-embedded tissue collection at follow-up for molecular studies analyzing inter-patient variation by microarrays. Patients in centers participating in sub-studies undergo quality of life and health economic assessment at baseline, 6 months, and 1, 2, and 5 years. These patients also undergo photographic assessment at baseline, 2 years, and 5 years. After completion of study treatment, patients are followed for 10 years.