Rtog Sarcoma Radiation Oncologists Reach Consensus On Gross Tumor Volume (Gtv) And Clinical Target Volume (Ctv) On Computed Tomography Images For Preoperative Radiotherapy Of Primary Soft Tissue Sarcoma Of Extremity In Rtog Studies

To develop an Radiation Therapy Oncology Group (RTOG) atlas delineating gross tumor volume (GTV), and clinical target volume (CTV) to be used for preoperative radiotherapy of primary soft tissue sarcoma of extremity. A consensus meeting was held during the RTOG semi-annual meeting in January 2010 to reach agreement about GTV and CTV delineation on computed tomographic images for preoperative radiotherapy of large, high-grade extremity sarcoma. Data were presented to address the local extension of sarcoma. Variations in GTV and CTV on test cases contoured by RTOG sarcoma radiation oncologists were reviewed. Extensive discussion ensued to develop optimal criteria for GTV and CTV delineation on CT planning images. A consensus was obtained on appropriate computed tomography image-based GTV and CTV for high-grade large extremity sarcoma. GTV is defined as gross tumor defined by MRI T1 plus contrast images. Fusion of MRI and CT is recommended to delineate the GTV for radiotherapy planning, but this is optional. CTV for large high-grade sarcomas typically includes GTV plus 3 cm margins in the longitudinal (proximal and distal) directions, and suspicious edema (defined by MRI T2 images). If this causes the field to extend beyond the compartment, the field can be shortened to include the end of a compartment. The radial margin from the lesion should be 1.5 cm including any portion of the tumor not confined by an intact fascial barrier or bone or skin surface. This report serves as the template for the definition of GTV and CTV to be used in preoperative radiotherapy of extremity sarcoma in prospective RTOG trials. These resources are available as web-based images as well as descriptive format through RTOG. This is expected to improve target volume consistency and allow for more rigorous evaluation of the benefits and risks of sarcoma radiotherapy, as well as new treatment techniques.