Accelerated Partial Breast Irradiation Is Safe and Effective Using Intensity-Modulated Radiation Therapy in Selected Early-Stage Breast Cancer

APBI can be safely and effectively administered using IMRT. In retrospective analysis, IMRT enabled the achievement of normal tissue dose constraints as outlined by Radiation Therapy Oncology Group 04-13/NSABP B-13 while providing excellent conformality for the CTV. Local control and cosmesis have remained excellent at current follow-up, with acceptable rates of acute/late toxicities. Our data suggest that cosmesis is dependent on target volume size. Further prospective multi-institutional trials should be performed to evaluate IMRT to deliver APBI.