Hypofractionation for breast cancer radiotherapy is attracting considerable attention.1 Compared with conventional therapy, hypofractionation delivers a full course of treatment in fewer sessions, which may improve patient convenience and reduce treatment costs. There is a growing trend to extend the therapy’s indication to regional nodal irradiation (RNI). The question is whether this is wise. We assessed meta-analyses of breast cancer radiotherapy and have found cause for caution in extending the use of hypofractionation to RNI until data from prospective clinical trials become available. Data needed to improve decision making for extending hypofractionation use may include short- and long-term data on the repercussions of this therapy for lung and heart function and noncancer morbidity/mortality.