The PET- Retroperitoneal Sarcoma Study

Retroperitoneal sarcoma(RPS) is a rare cancer that is difficult to cure as it typically presents as a very large abdominal mass, and complete removal with clear margins is challenging . This study will focus on improving the outcomes of surgery by treating RPS before surgery, to make resection more effective. The role of chemotherapy as a preoperative treatment for RPS is highly controversial. Response to chemotherapy is unpredictable and if the patient's tumour progresses instead of responding, the window of opportunity for resection will be lost. Conventional cross sectional imaging (CT scan) is inadequate to measure response to chemotherapy until 5-6 cycles have been given, possibly with no improvement. Thus it is critical to develop an earlier and reliable way to assess response. Functional imaging by PET scan is used in other tumour types to identify early response to treatment. PET imaging may provide a more meaningful assessment of RPS response to systemic therapy much earlier in the course of treatment than conventional imaging, allowing timely modification of the treatment plan. This study will define the role of PET imaging in evaluating early response to systemic therapy in high grade RPS, improving patient treatment.