Objective: To critically review the theoretical and actual risks and benefits of accelerated partial breast irradiation (APBI) after breast-conserving surgery.
Summary Background Data: Because of rapid evolution of radiation therapy techniques related to brachytherapy and three-dimensional conformal radiation therapy, APBI has very recently come to the forefront as a potential local treatment option for women with breast cancer. This review aims to give an overview of the biologic rationale for APBI techniques, and benefits and limitations of APBI techniques.
Methods: The authors reviewed the currently available published world medical literature on breast-conserving surgery with and without postoperative irradiation; all studies involving partial breast irradiation, including brachytherapy, for breast cancer; and currently accruing and planned APBI trials. The focus of this review was the early results of treatment in terms of toxicity, complications, cosmesis, and local control.
Results: On average, approximately 3% of patients treated with breast-conserving surgery will have an in-breast local recurrence away from the original lumpectomy site with or without postoperative standard whole-breast irradiation. The results of phase I-II studies involving approximately 500 patients treated with APBI after breast-conserving surgery have been published. Although many of the studies have limited long-term follow-up and potential selection bias, early results suggest that toxicity, cosmesis, and local control are comparable to outcomes seen after breast-conserving surgery followed by standard whole-breast irradiation.
Conclusions: Recent advances in radiation delivery and published series of partial breast irradiation support large randomized trials comparing APBI with standard whole-breast irradiation after breast-conserving surgery.
At present, radiation therapy after breast-conserving surgery is generally delivered to the whole breast over a period of 5 to 6 weeks. Recently, however, rapidly emerging technological advances in radiation delivery have allowed the concept of accelerated partial breast irradiation (APBI) to quickly come to the forefront as a potential alternative to standard whole-breast irradiation after breast-conserving surgery. APBI refers to radiation therapy that is delivered over a shorter period than the standard 5 to 6 weeks (“accelerated”) and is delivered to only a portion of the breast (“partial”). Since the late 1990s, investigators at multiple institutions have been investigating the efficacy and safety of APBI. Initial results of several clinical trials of APBI have now been published. In this article, we will review the potential advantages of APBI, the biologic rationale for APBI, and the various methods of delivering APBI, each of their associated benefits and limitations, and a potential large randomized multidisciplinary trial evaluating APBI after breast conserving surgery for breast cancer.