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

RATIONALE: Radiation therapy uses high-energy x-rays to damage tumor cells. Giving radiation therapy before surgery may shrink the tumor so that it can be removed. It is not yet known whether surgery is more effective with or without radiation therapy. PURPOSE: This randomized phase III trial is studying surgery alone to see how well it works compared to radiation therapy together with surgery in treating patients with primary soft tissue sarcoma of the retroperitoneum or pelvis.