Short Course Radiation Treatment for Patients with Primary or Locally Recurrent Retroperitoneal Sarcoma Prior to Surgery

Eligibility Criteria

• * Participants must have a histologically confirmed STS of the retroperitoneal space or infra-peritoneal spaces of pelvis
• * Participant must have radiologically measurable disease (RECIST 1.1), as confirmed by abdomino-pelvic CT or MRI
• * Participant must have primary, locally recurrent, or metastatic disease requiring treatment of the retroperitoneal mass
• * Tumor must be suitable for radiotherapy and surgery based on pre-treatment CT scan/MRI in multidisciplinary discussion with surgeon and radiation oncologist (anticipated macroscopically complete resection, R0/R1 resection)
• * Age: 18 years or older
• * ECOG performance status ≤2
• * Absence of history of bowel obstruction, mesenteric ischemia, or severe chronic inflammatory bowel disease.
• * Normal renal function (calculated creatinine clearance ≥50 mL/min)
• * Normal bone marrow and hepatic function (white blood cell count ≥2·5 × 10⁹ cells per L, platelet count ≥80 × 10⁹ cells per L, and total bilirubin \<2 times upper limit of normal)
• * Women of child-bearing potential must have a negative pregnancy test within 3 weeks prior to the first day of study treatment
• * Patients capable of childbearing/reproductive potential should use adequate contraception
• * Ability to understand and the willingness to sign a written informed consent document
• * Sarcoma originating from bone structure, abdominal or gynecological viscera
• * Any of the following histological subtypes: gastrointestinal stromal tumor, rhabdomyosarcoma, primitive neuroectodermal tumor or other small round blue cell sarcoma, osteosarcoma, chondrosarcoma, aggressive fibromatosis, or sarcomatoid or metastatic carcinoma
• * Prior RT to the RPS
• * Prior abdominal or pelvic irradiation for other prior malignancy or other disease
• * Prior different invasive malignancy may be eligible per the discretion of the treating investigator and review by the Principal Investigator (PI)
• * Prior chemotherapy or immunotherapy within 6 weeks of start of RT
• * Pregnant women are excluded from this study because RT has the potential for teratogenic or abortifacient effects.
• * HIV-positive individuals on combination antiretroviral therapy are ineligible because of the potential for increased sensitivity to RT