A Prospective Randomized Trial of Pre-Operative IMRT+Surgery Versus Surgery Alone For Primary Retroperitoneal Sarcoma

Inclusion Criteria:

* Patients with primary retroperitoneal/pelvic soft tissue sarcoma.
* Gross total resection (RO or R1) must be feasible.
* No prior chemotherapy, immunotherapy or radiotherapy is allowable.
* Patients should be over 18 years of age and capable of providing informed consent indicating awareness of the investigational nature of this trial, in keeping with hospital policy.
* Karnofsky performance status of \>= 70 %
* No other concurrent chemotherapy, immunotherapy or radiotherapy is allowable.
* Adequate organ function defined as follows: absolute granulocytes \>= 1,500/mm 3, platelets \>= 150,000/mm 3, serum bilirubin \<= 1.5 mg/dl, serum creatinine \<= 1.5 mg/dl.
* Written informed consent (study specific) must be obtained from each patient prior to entering the study.
* Patients should be willing to be followed at Memorial Sloan-Kettering Cancer Center during the course of treatment and follow-up.
* Patients must be able to get IMRT radiotherapy at Memorial Sloan-Kettering Cancer Center

Exclusion Criteria:

* Patients presenting with primary non-retroperitoneal soft tissue sarcoma or recurrent retroperitoneal sarcoma.
* Patients who are deemed unresectable by clinical/imaging criteria.
* Patients with histologic diagnosis of gastrointestinal stromal sarcoma, desmoplastic small round cell tumor, desmoid, Ewing's sarcoma, PNET, adenosarcoma, granular cell tumor, mesothelioma or rhabdomyosarcoma are excluded from the study.
* Patients with known metastatic disease, or those with radiologically evident metastases.
* Patients with clinically significant heart disease (NYHA Class III/IV), history of active angina or myocardial infarction within 6 months, history of significant ventricular arrhythmia requiring medication with antiarrhythmics or a history of clinically significant conduction system abnormality. Patients with any of the above conditions who are seen by a cardiologist at MSKCC and are found to be an acceptable risk for surgery will be allowed to participate in this study.
* Patients with any active concurrent malignancy other than non-melanoma skin cancers or carcinoma-in situ of the cervix. Patients with previous malignancies but without evidence of disease for \> 5 years will be eligible.
* Women who are pregnant.
* Patients currently participating in other clinical trials the requirements of which may preclude their complete involvement in this study
* Patients with serious intercurrent infections or non-malignant uncontrolled illnesses