Tailored Radiotherapy for Breast Cancer Stages I and II: Technical Aspects

Abstract

The equivalence between conservative surgery (CS) and radiation therapy (RT), and mastectomy for the treatment of patients with early stage breast cancer, with respect to local control and survival, has been demonstrated conclusively in multiple phase III trials with long-term follow-up [1, 2]. Despite the overwhelming success of this treatment approach, the number of eligible patients managed with breast-conserving therapy (BCT) remains surprisingly low. Factors contributing to the underutilization of breast-conserving techniques have not been well defined but appear, in part, to be related to the time, cost, and toxicity associated with delivering standard RT after lumpectomy [3]. A typical course of whole-breast external beam RT followed by a boost to the tumor bed generally requires 5–7 weeks to complete. This can present significant logistical problems for many patients, particularly the elderly and/or those who reside a considerable distance from a radiation treatment facility. Due to potential obstacles associated with the successful delivery of standard BCT, research has focused on defining effective and safe treatment strategies that reduce or eliminate the time-consuming process of delivering a tumoricidal dose of RT to the whole breast after CS, or in reducing the acute and chronic toxicity of standard therapy. To this end, studies have been developed with the goals of either: (1) defining subsets of patients who do not require RT after lumpectomy, (2) establishing whether or not a boost of RT is beneficial after whole-breast RT, (3) exploring methods of delivering RT in a substantially shortened treatment time after CS, or (4) further improving the safe delivery of whole-breast RT in those patients requiring such treatment. In this chapter, we will review published data on the multitude of studies that have been designed and implemented to test these hypotheses. In addition, we will objectively assess these treatment strategies with respect to their potential value in achieving their ultimate goals. Finally, we will also review new radiotherapeutic techniques designed to improve the efficacy of standard wholebreast RT.