RecruitingPhase 1ProcedureStudy of Preoperative Radiation Therapy in Participants With Resectable Recurrent Abdominal Adrenocortical CarcinomaBackground: Adrenocortical carcinoma (ACC) is a rare cancer of the adrenal glands. ACC often returns after tumors are removed with surgery. Less than 35% of people with ACC survive 5 years after diagnosis. Objective: To test a new type of external beam RT before surgery in people with ACC. Eligibility: People aged 18 years and older with ACC that came back after treatment but may be safely removed with surgery. Design: Participants will be screened. They will have a physical exam with blood and urine tests. They will have tests of their heart function. They will have imaging scans. A small sample of tumor tissue may be collected if one is not available. They will undergo laparoscopy: Small incisions will be made in the abdomen so that a thin tube with a light and camera can be inserted to view the organs. RT comes from a machine that aims radiation at tumors. Participants will receive preoperative RT in daily fractions over approximately 2-3 weeks, followed by a planned surgical resection about 4 weeks after the completion of RT. Visits will last 30 to 60 minutes. Participants will undergo surgery to remove their tumors about 4 weeks after they finish RT. They will stay in the hospital 1 to 3 weeks after surgery. Participants will have follow-up visits for 10 years after surgery.