RecruitingPhase 3Radiation therapyConventionally Fractionated vs. Hypofractionated Comprehensive Nodal Irradiation for Breast Cancer Using Pencil Beam Scanning Proton TherapyThe purpose of this research study is to learn more about the effects of using proton radiation therapy delivered over a shorter course of treatment (3 weeks) compared with a longer, standard course of treatment (5 weeks) for women with breast cancer who require radiotherapy to the breast/chest wall and regional lymph nodes.