Over the past two decades, breast conserving therapy (BCT) has become a major treatment modality for Stage I and II breast carcinoma. The major advantages of breast conserving therapy are superior cosmetic outcome and the reduced emotional and psychological trauma afforded by this procedure compared with conventional mastectomy. The principal disadvantage of BCT is its more complex and prolonged treatment regimen requiring approximately 6 weeks of external beam radiation therapy that poses problems for some patients such as the working woman, elderly patients, and those who live at a significant distance from a treatment center. These factors, along with the patient's geographic location, result in a smaller fraction of the patients who currently meet eligibility criteria for BCT actually receiving it, despite its cosmetic and probable psychological advantages. The logistical problems of BCT are primarily related to the protracted course of external beam radiation therapy to the whole breast. While some investigators reported what they believe to be acceptable local control rates in carefully selected patients treated by wide local excision without radiation therapy, the criteria for patient selection are controversial and poorly defined and probably restrict the access of many patients to breast conserving therapy.