Surgery With or Without Radiation Therapy in Treating Patients With Primary Soft Tissue Sarcoma of the Retroperitoneum or Pelvis

OBJECTIVES: Primary * Compare progression-free survival of patients with primary soft tissue sarcoma of the retroperitoneum or pelvis treated with surgery with vs without preoperative radiotherapy. Secondary * Compare the toxicity and complications associated with these regimens in these patients. * Compare the rate of microscopically complete surgical resection in patients treated with these regimens. * Compare the overall survival rate of patients treated with these regimens. OUTLINE: This is a randomized, multicenter study. Patients are stratified according to tumor grade (low \[G1\] vs intermediate \[G2\] vs high \[G3/4\]), tumor size (\< 15 cm vs ≥ 15 cm), and tumor histology (liposarcoma vs non-liposarcoma). Patients are randomized to 1 of 2 treatment arms. * Arm I: Patients undergo surgery. * Arm II: Patients undergo preoperative radiotherapy once daily, 5 days a week, for 5.5 weeks. Within 28-63 days after the completion of radiotherapy, patients undergo surgery. In both arms, treatment continues in the absence of disease progression or unacceptable toxicity. Patients are followed at 28 days, 4 months, every 6 months for 5 years, and then annually for 5 years. PROJECTED ACCRUAL: A total of 370 patients (185 per treatment arm) will be accrued for this study within 4.5 years.