OBJECTIVES: I. Evaluate the technical feasibility and reproducibility, cosmetic results, complication rates, and local cancer control rate experience with brachytherapy used as the sole method of radiotherapy in women with stage I/II breast cancer treated with tylectomy who have histologically assessed negative surgical margins, less than 4 positive axillary nodes, and no extracapsular nodal extension or extensive intraductal component. II. Reduce the total treatment time of breast irradiation from 6 weeks to 4-5 days in these patients.