A Multi-Institutional Registry for CyberKnife Stereotactic Accelerated Partial Breast Irradiation (CK-SAPBI)

Radiotherapy for breast cancer is delivered using several whole breast and partial breast approaches. The optimal approach is unknown. The utilization of partial breast irradiation is growing due to the convenience of fewer fractions versus fifteen- thirty treatments required with conventional or hypofractionated whole breast radiation therapy. Early results with partial breast techniques are promising, showing similar cancer control and toxicity. There is a large body of mature Phase I/II and preliminary Phase III data available exploring the replacement of WBI with an accelerated course of radiation therapy restricted to the region around the tumor bed (accelerated Partial Breast Irradiation, aPBI) using a variety of techniques. For appropriately selected patients treated with modern techniques, the results are encouraging and the techniques have been shown to be safe, tolerable, and highly reproducible with outcomes similar to WBI. Currently, there is limited data assessing the quality of life, cosmetic and oncologic outcomes following stereotactic partial breast irradiation in a large patient population. Our study will be the first essential step in aggregating the outcomes of patients undergoing this type of external beam irradiation in a large patient population.