This study conducted by the MD Anderson group reported clinical results of 42 children with Ewing sarcoma treated with protons to a median total dose of 54 GyRBE. Treated sites included the spine (45%), pelvis/sacrum (26%), skull/cranium (14%), extraosseous (10%), and chest wall (5%). The 4-year LC, PFS, and OS rates were 83%, 71%, and 86%, respectively. All local failures (n = 6) were in-field failures. There was only one instance of acute Grade 3 febrile neutropenia and two late Grade 3 toxicities (dental caries and esophageal stricture). The authors concluded that PT provided comparable LC to that of historical photon-RT.