Accelerated partial breast irradiation for early-stage breast cancer: controversies and current indications for use

Radiation therapy options for early-stage breast cancer have evolved during the past 40 years. Several choices are currently available to certain patient subsets that allow radiation oncologists to individualize care. Multiple phase II and several phase III trials have been published that support the safety and efficacy of accelerated partial breast irradiation (APBI) as part of breast conservation in selected patients. In contrast, a recent large retrospective analysis of patients aged 67 or older who received brachytherapy for APBI has raised concerns about its effectiveness. As the radiation community awaits results from NSABP B-39/RTOG 0413, the largest randomized trial of whole breast radiation therapy (WBRT) versus APBI, to provide more conclusive data, many academic and private radiation oncology practices are utilizing APBI off-protocol to treat early-stage breast cancer patients. Because of this, the American Society for Radiation Oncology (ASTRO) published a consensus statement in 2009 to aid in proper patient selection (Table 1). Until more definitive data is garnered, we advocate strict adherence to these selection criteria to ensure optimal outcomes. Specifically, we caution against the use of APBI in lymph node-positive disease outside of a clinical trial. There is a paucity of comparative data to guide oncologists in selection of the best APBI delivery method. The current NSABP B-39/RTOG 0413 trial allows any of the three most common forms of delivery to be utilized (multicatheter interstitial brachytherapy, balloon intracavitary brachytherapy, and external beam 3D conformal therapy) and will be instrumental to compare outcome differences between these methods.