Partial Breast Irradiation

The benefit of post-lumpectomy and postmastectomy radiation therapy (RT) in improving local control and overall survival has been demonstrated through multiple randomized trials. Historical “conventional” fractionation consisted of 25 fractions of 2 Gy to the whole breast with an additional boost to the primary tumor bed cavity or the mastectomy scar. Over the last decade, multiple randomized studies explored hypofractionated whole-breast irradiation (WBI), making 40 Gy in 15 fractions and similar regimens, and more recently 26 Gy in 5 fractions for breast/chest wall only, as new standards. Another approach, partial breast irradiation (PBI), has been explored in the post-lumpectomy setting to target only the primary tumor bed, representing an alternative and attractive approach for low-risk patients.