RecruitingPhase 2Radiation therapyAdjuvant Therapy in POLE-Mutated and p53-Wildtype/NSMP Early Stage Endometrial Cancer RAINBO BLUE & TAPERThis protocol tests de-escalated adjuvant treatment in patients with POLE-mutated or p53wt/NSMP (p53 wildtype/no specific molecular profile) early-stage endometrial cancer (EC). Patients may be enrolled in one of two sub-studies * EN10.A/RAINBO BLUE: POLE-mutated EC * EN10.B/TAPER: p53 wildtype / NSMP EC