3-Dimensional Conformal Radiation Therapy or Internal Radiation Therapy After Breast-Conserving Surgery in Treating Women With Stage I or Stage II Breast Cancer

OBJECTIVES: Primary * To compare the rate of successfully delivered accelerated partial breast irradiation (APBI) using 3-dimensional conformal radiation therapy vs multi-catheter interstitial brachytherapy in women with stage I or II invasive ductal carcinoma of the breast. * To establish potential patient participation in ongoing phase III clinical trials (e.g., NSABP-B-39, GEC-ESTRO, RAPID, MPORT, and IRMA) that compare APBI to standard whole-breast irradiation. Secondary * To assess acute radiation-induced toxicity in these patients as assessed by NCI CTCAE version 3.0. * To assess long-term radiation-induced toxicity in these patients as assessed by RTOG-EORTC scale. * To assess the incidence and type of adverse events in the breast of these patients. * To assess the incidence and type of procedure-related complications in these patients. * To determine local control and pattern of recurrence in these patients. * To determine disease-free survival (distant and recurrence-free survival) of these patients. * To determine overall survival of these patients. * To assess cosmesis in these patients as assessed by the Breast Cancer Treatment Outcome and RTOG scales. * To assess treatment-related symptoms in these patients as assessed by the Breast Cancer Treatment Outcome scale. OUTLINE: Patients are randomized to 1 of 2 treatment arms. Patients with a lumpectomy cavity/whole breast ratio 25-30% are assigned to treatment in arm II. * Arm I: Patients undergo accelerated partial breast irradiation (APBI) using 3-dimensional conformal radiation therapy twice daily over 5-10 days (total of 10 fractions) in the absence of disease progression or unacceptable toxicity. * Arm II: Patients undergo APBI using multi-catheter interstitial brachytherapy twice daily over 5-10 days (total of 10 fractions) in the absence of disease progression or unacceptable toxicity. Patients complete quality-of-life questionnaires at baseline, on the last day of treatment, at 4 and 24 weeks after completion of treatment, and then annually for 3 years. After completion of study treatment, patients are followed periodically for at least 5 years.