Surgery With or Without Radiation Therapy in Untreated Nonmetastatic Retroperitoneal Sarcoma

RATIONALE: Radiation therapy uses high-energy x-rays to kill tumor cells. Giving radiation therapy before surgery may make the tumor smaller and reduce the amount of normal tissue that needs to be removed. It is not yet known whether surgery is more effective with or without radiation therapy in treating nonmetastatic retroperitoneal soft tissue sarcoma.

PURPOSE: This randomized phase III trial is studying radiation therapy followed by surgery to see how well it works compared with surgery alone in treating patients with previously untreated nonmetastatic retroperitoneal soft tissue sarcoma.

OBJECTIVES:

Primary

* To assess whether there is a difference in abdominal recurrence-free survival between retroperitoneal soft tissue sarcoma patients undergoing curative intent surgery alone and those undergoing preoperative radiotherapy followed by curative-intent surgery.

Secondary

* To assess whether there is a difference in metastasis-free survival, abdominal recurrence-free interval, and overall survival between these patients.
* To assess tumor response in patients undergoing preoperative radiotherapy.
* To assess toxicity of preoperative radiotherapy given prior to curative-intent surgery in these patients.

OUTLINE: This is a multicenter study. Patients are stratified according to institution and WHO performance status (0-1 vs 2). Patients are randomized to 1 of 2 treatment arms.

* Arm I: Patients undergo surgical resection of the tumor mass within 4 weeks following randomization.
* Arm II: Patients undergo 3-dimensional conformal radiation therapy (RT) or intensity-modulated RT within 8 weeks after randomization. RT continues 5 days a week for approximately 5.5 weeks. Patients undergo surgical resection of the tumor mass within 4-8 weeks after the completion of RT.

Tumor tissue, normal abdominal wall fat, and peripheral blood may be collected during surgery to identify new prognostic factors for translational research.

After completion of study therapy, patients are followed at day 60 post-surgery and every 6 months thereafter.

Eligibility Criteria:
DISEASE CHARACTERISTICS:

* Histologically confirmed retroperitoneal sarcoma (RPS) by local pathologist, imaging-guided or surgical biopsy, including the following:

  * Primary soft tissue sarcoma of retroperitoneal space or infra-peritoneal spaces of pelvis
  * Sarcoma not originated from bone structure, abdominal, or gynecological viscera
  * Unifocal tumor (not multifocal disease)
  * Absence of extension through the sciatic notch or across the diaphragm
* The following histological sub-types are not allowed:

  * Gastrointestinal stromal tumor (GIST)
  * Rhabdomyosarcomas
  * Primitive neuroectodermal tumor (PNET) or other small round blue cells sarcoma
  * Osteosarcoma or chondrosarcoma
  * Aggressive fibromatosis
  * Sarcomatoid or metastatic carcinoma
* No metastatic disease
* Untreated disease
* Tumor must be operable and suitable for radiotherapy, based on the following criteria:

  * Pre-treatment CT scan/MRI and multidisciplinary consultation with surgeon, radiation oncologist, and radiologist (anticipated macroscopically complete resection, R0/R1 resection)

    * No surgery anticipated to be R2 on the CT scan before randomization
  * Must have American Society of Anesthesiologist (ASA) score ≤ 2
  * None of the following unresectable criteria:

    * Involvement of superior mesenteric artery
    * Involvement of aorta
    * Involvement of bone
* Must have radiologically measurable disease (RECIST 1.1), as confirmed by abdomino-pelvic CT (with IV and PO contrast) or MRI (with IV contrast)

PATIENT CHARACTERISTICS:

* WHO performance status 0-2
* WBC ≥ 2,500/mm\^3
* Platelet count ≥ 80,000/mm\^3
* Total bilirubin \< 1.5 times the upper limit normal
* Calculated creatinine clearance normal
* Functional contra-lateral kidney to the side involved by the RPS as assessed by intravenous pyelogram
* Adequate cardiac function (NYHA class I-II)
* ECG normal (without clinically significant abnormalities)
* No history of any of the following disorders:

  * Bowel obstruction
  * Mesenteric ischemia
  * Severe chronic inflammatory bowel disease
* Negative pregnancy test
* Not pregnant or nursing concurrently and for at least 1 month after the surgery
* Fertile patients must use effective contraception during the study treatment period and for at least 1 month after the surgery
* No co-existing malignancy within the past 5 years, except for adequately treated basal cell carcinoma of the skin or carcinoma in situ of the cervix
* No psychological, familial, sociological, or geographical condition potentially hampering compliance with the study protocol and follow-up schedule

PRIOR CONCURRENT THERAPY:

* No prior surgery (excluding diagnosis biopsy), radiotherapy, or systemic therapy
* No prior abdominal or pelvic irradiation for another prior malignancy or other disease
* No concurrent systemic anticancer treatment (chemotherapy, molecular-targeted therapy)
* No postoperative radiotherapy planned