Preoperative Ultra-hypofractionated Radiotherapy Followed by Surgery for Retroperitoneal Sarcoma (FUSION-01)

This trial is investigating whether giving a short, concentrated course of radiation before surgery (called ultra-hypofractionated radiotherapy) is a safe and effective treatment for retroperitoneal sarcoma — a rare soft tissue cancer found deep in the abdomen. **You may be eligible if...** - You have a primary soft tissue sarcoma located in the retroperitoneal space (deep abdomen) or pelvic area - Your cancer did not originate from bone, abdominal organs, or gynecological organs - All of your tumor can be safely included in a single radiation field - You are fit for surgery following radiation **You may NOT be eligible if...** - Your cancer has spread to distant sites (metastatic disease) - Your tumor extends through the sciatic notch or certain sensitive areas where radiation is unsafe - You have received prior radiation to the treatment area - You have certain connective tissue diseases that increase radiation sensitivity Talk to your doctor to see if this trial is right for you.