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

Inclusion Criteria: * Primary soft tissue sarcoma of retroperitoneal or infra-peritoneal spaces of pelvis * Sarcoma not originated from bone structure, abdominal or gynecological viscera * All disease can be included safely within one radiotherapy field * Absence of extension through the sciatic notch or across the diaphragm * Histologically proven, excluding the following subtypes: Gastro-intestinal stromal tumors (GIST), rhabdomyosarcoma, PNET or other small round blue cells sarcoma, osteosarcoma or chondrosarcoma, aggressive fibromatosis, sarcomatoid or metastatic carcinoma * ECOG performance status 0 to 2 * American Society of Anesthesiologist (ASA) score ≤2 * Normal renal function: Calculated Creatinine Clearance ≥50ml/min（by Cockcroft-Gault formula）and functional contralateral kidney by differential renal isotope scan * Normal bone marrow and hepatic function. * Contraception was needed for female patients of child-bearing age, or male patients whose partner had child-bearing age * expected life expectancy longer than 5 years * Written consent form was given prior to treatment * Can safely be treated by radiotherapy and surgery Exclusion Criteria: * metastatic disease * Tumor was previously treated by radiotherapy * Involvement of liver, pancreatic head or duodenum