High Precision RT For Soft-Tissue Sarcoma

Primary Outcome Measures:

• To determine the extent of inter-fractional and intra-fractional movement of the GTV during radiotherapy treatments. [ Time Frame: 3 years ]
  To quantify and describe the movement of the tumor during and between radiotherapy treatments using imagings acquired during the course of radiotherapy planning and treatments.
  
  
• To assess the acute and long-term toxicity of pre-operative radiotherapy as a function of the dose given to normal tissues and its impact on patient quality of life. [ Time Frame: 10 years ]
  To describe the effect of radiotherapy to the patient by measuring the acute and long-term side-effects of radiation therapy.
  
  

Secondary Outcome Measures:

• Describe variations in the volume and shape of the GTV over the course of the treatment and need for adaptive therapy. [ Time Frame: 3 years ]
  To measure and better define the response of the tumor to radiotherapy during treatments.
  
  
• Correlate the pattern of local recurrence with the dose of radiation delivered accounting for motions and volume changes of target structures. [ Time Frame: 10 years ]
  To determine whether there is a pattern of local relapse with the actual dose of radiation delivered to the tumor environment when tumor volumetric and positional changes are taken into account.
  
  

Soft-tissue sarcomas (STS) that arise from the retroperitoneum are rare malignancies that are anatomical located deep within the abdominal area and thus pose challenges to surgical and radiotherapeutic management of the patient. As a result, the local control and overall survival for patients with retroperitoneal sarcomas (RPS) are worse than STS from the extremities. Current treatment strategy involves pre-operative radiotherapy followed by surgery. Use of intensity-modulated radiotherapy (IMRT) in RPS had allowed for more conformal treatments with the aim of sparing normal tissues from high doses of irradiation. Yet the accuracy and coverage of IMRT depend highly on target motion, and little is known about the motion of RPS during the course of radiotherapy. As well, RPS are commonly in close proximity to sensitive organs for which the long-term toxicity and effect on quality of life secondary to radiation is unknown. The current study seeks to evaluate the extent of tumor motion during radiotherapy and the impact of radiotherapy to patient toxicity and quality of life. At the conclusion of this study, our results will hopefully identify the optimum PTV, the importance of different normal tissues and their dose-volume constraints, the role of image guidance, and the potential for dose escalation in the treatment of RPS.