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

DISEASE CHARACTERISTICS:

* Histologically confirmed primary soft tissue sarcoma of the retroperitoneum or pelvis (e.g., iliac fossa)

  * The following histologies are eligible:

    * Alveolar soft part sarcoma
    * Anaplastic sarcoma
    * Angiosarcoma
    * Atypical lipomatous tumor (low-grade liposarcoma)
    * Clear cell sarcoma
    * Epithelioid sarcoma
    * Fibrosarcoma
    * Leiomyosarcoma
    * Liposarcoma (all subtypes)
    * Malignant fibrous histiocytoma
    * Malignant peripheral nerve sheath tumor
    * Myxofibrosarcoma
    * Neurofibrosarcoma
    * Spindle cell sarcoma
    * Synovial sarcoma
    * Unclassified sarcoma
  * The following histologies are not eligible:

    * Rhabdomyosarcoma
    * Extraosseous Ewing's sarcoma
    * Primitive neuroectodermal tumor
    * Osteosarcoma
    * Chondrosarcoma
    * Aggressive fibromatosis (desmoid tumor)
    * Gastrointestinal stromal tumor
    * Sarcomatoid carcinoma
    * Hemangiopericytoma
* Retroperitoneal sarcomas located predominantly in the retroperitoneum extending across the inguinal ligament into the abdominal wall are allowed provided that ≥ 90% of the tumor volume is located within the retroperitoneal space

  * No bowel obstruction OR history of previous bowel obstruction attributed to retroperitoneal tumor
* Primary non-visceral retroperitoneal masses consistent with sarcoma allowed provided diagnoses of carcinoma, melanoma, and lymphoma are excluded by immunohistochemistry
* Measurable gross disease by abdominopelvic CT scan (with IV and oral contrast) or MRI (with IV contrast)
* Patients must have undergone radiotherapy consultation within the past 30 days to confirm the feasibility of preoperative external-beam radiotherapy
* Patients must have undergone surgical consultation within the past 30 days to confirm and document the feasibility of macroscopically complete resection

  * No prior macroscopically incomplete (R2) resection (i.e., partial debulking or subtotal tumor resection with gross residual disease)
* No pelvic sarcoma extending through the sciatic notch
* No clinical or radiographic evidence of probable metastatic disease

  * Equivocal pulmonary or liver lesion allowed provided the likelihood of metastatic disease is small
* No sarcoma arising from bone or any retroperitoneal viscus (except the kidney)
* No sarcoma extending across the diaphragm into the thorax
* No recurrent retroperitoneal tumor
* No multifocal disease

PATIENT CHARACTERISTICS:

Age

* 18 and over

Performance status

* ECOG 0-1 OR
* Zubrod 0-1

Life expectancy

* Not specified

Hematopoietic

* WBC ≥ 2,500/mm\^3
* Platelet count ≥ 80,000/mm\^3

Hepatic

* Bilirubin ≤ 1.5 times upper limit of normal (ULN)
* AST ≤ 2.5 times ULN
* Albumin normal\* NOTE: \*Higher levels allowed

Renal

* Creatinine normal
* BUN normal
* Functional kidney confirmed by intravenous pyelogram and/or differential renal isotope scan

Other

* Not pregnant
* Negative pregnancy test
* Fertile patients must use effective contraception during and for 3 months after study participation
* No other malignancy within the past 5 years (except effectively treated basal cell or squamous cell skin cancer) unless patient was curatively treated AND is at low risk for recurrence

PRIOR CONCURRENT THERAPY:

Chemotherapy

* No concurrent chemotherapy for primary tumor

Radiotherapy

* No prior abdominal or pelvic irradiation
* No concurrent intraoperative or postoperative radiotherapy for primary tumor

Surgery

* See Disease Characteristics