PET scans may help guide chemo for rare abdominal cancer

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Tumour-related criteria * Primary soft tissue sarcoma of retroperitoneal space or infra-peritoneal spaces of pelvis * Sarcoma not originated from bone structure, abdominal or gynecological viscera * Unifocal tumour (not multifocal disease) * Absence of extension through the sciatic notch or across the diaphragm * Histologically-proven RPS (local pathologist/ imaging-guided or surgical biopsy), only including the following histological sub-types: * High grade Leiomyosarcoma * High grade Dedifferentiated Liposarcoma * Tumour not previously treated (no previous surgery -excluding diagnosis biopsy-, radiotherapy or systemic therapy) * Tumour both operable and suitable for chemotherapy (This will be based on pretreatment CT scan/MRI and multidisciplinary consultation with surgeon medical oncologist and radiologist (anticipated macroscopically complete resection, R0/R1resection) * Patients for whom surgery is expected to be R2 on the CT-scan before randomization are not eligible * Patients must have American Society of Anesthesiologist (ASA) score ≤ 2 (see Appendix G) * The criteria for non-resectability are: * (i) involvement of superior mesenteric artery * (ii) involvement of aorta * (iii) involvement of bone * distant metastatic disease * Patient must have radiologically measurable disease (RECIST 1.1) Patient-related criteria * ≥ 18 years' old * WHO performance status ≤ 2 (see Appendix C) * Absence of history of bowel obstruction or mesenteric ischemia or severe chronic inflammatory bowel disease * Normal renal function: * Calculated creatinine clearance within normal value Functional contra-lateral kidney to the side involved by the RPS as assessed by intravenous pyelogram (done during the baseline CT-scan) or differential renal isotope scan * Normal bone marrow and hepatic function: * White Blood cells ≥ 2.5 x10 9 cells/L * Platelets ≥ 80 x10 9 cells/L * Total bilirubin \< 1.5 time the institutional upper limit normal of value (ULN) * Adequate cardiac function: less or equal to NYHA II * Normal 12 lead ECG (without clinically significant abnormalities) * No co-existing malignancy within the last 5 years except for adequately treated basal cell carcinoma of the skin or carcinoma in situ of the cervix * No prior abdominal or pelvic irradiation for other prior malignancy or other disease * Absence of any psychological, familial, sociological or geographical condition potentially hampering compliance with the study protocol and follow-up schedule * Excluding patients who presented after incomplete resection and underwent immediate completion surgery. Exclusion Criteria: * Age\< 18 years * Recurrent tumour * Benign retroperitoneal tumours * Presence of second active cancer * Serious psychiatric disease that precludes informed consent or limits compliance * impossible to ensure adequate follow up