Keywords: خانواده یورونگ یوینگ از تومورها; PBT; proton beam therapy; ESFT; Ewing sarcoma family of tumors; VDC-IE; vincristine, doxorubicin, cyclophosphamide, ifosfamide and etoposide; UTH; University of Tsukuba Hospital; EFS; event-free survival; OS; overall survival; DFS; disease-free survival;