Accelerated Partial Breast Irradiation and Hypofractionated Whole Breast Radiation

Breast conservation therapy (BCT), consisting of local excision of the breast tumor to achieve negative margins followed by whole breast irradiation, is standard treatment for early-stage breast cancer. The conventional radiotherapy course treats the entire breast, typically followed by a boost to the tumor bed over six to seven weeks. While the efficacy and cosmetic outcomes of conventionally fractionated whole breast radiation are well-established, two strategies are being investigated to address the lengthy treatment time associated with adjuvant radiotherapy for early-stage breast cancer. Accelerated partial breast irradiation (APBI) involves treatment to the tumor bed plus a small margin, allowing completion of therapy in five days or less. A variety of techniques, each with unique advantages and disadvantages, is currently under investigation for delivering APBI. Hypofractionated whole breast radiation (hWBRT) involves treating the entire breast with larger daily doses of radiation over three to four weeks. This article reviews the principles behind APBI and hWBRT, the indications for each technique, and relevant data supporting their use.