Accelerated partial breast irradiation

Traditionally, the treatment for early-stage breast cancer has included lumpectomy followed by whole breast radiotherapy over 5-6 weeks. Due to the inconvenience and cost of this schedule along with concern that targeting the whole breast may be overtreatment from some patients, accelerated partial breast irradiation (APBI) has been explored as an alternative radiotherapy strategy. APBI shortens breast radiotherapy to 1 week or less by increasing the dose per fraction while decreasing the treatment volume to the tumor bed alone. Generally, APBI is restricted to patients with the lowest risk disease; however, the results of ongoing trials may potentially broaden eligibility. APBI can be accomplished via multiple techniques including (1) multicatheter interstitial brachytherapy, (2) balloon-based brachytherapy (MammoSite), (3) external beam radiotherapy, and (4) intraoperative radiotherapy. These methods differ in their degree of invasiveness, treatment time, radiation dose, and exact volume of breast tissue irradiated. Based on Phase I, II, and more recently Phase III studies, each of these techniques can achieve excellent local control rates with low toxicity when performed correctly. The anticipated publication of several large Phase III studies in the coming years will help to further define patient selection criteria and determine the appropriate APBI technique for each clinical setting.