Background
RTOG Sarcoma Radiation Oncology Working Group consensus atlas standardizing GTV (gross tumor volume) and CTV (clinical target volume) definitions for preoperative RT of primary extremity soft tissue sarcoma (STS). Consensus meeting January 2010; atlas developed for use in RTOG cooperative-group trials.
Interventions and follow up
Treatment: RTOG consensus contouring atlas for GTV and CTV definitions in STS radiotherapy (preoperative and postoperative)
Primary endpoint: Consensus volumetric definitions
mFollow up: Not applicable
Primary endpoint: Consensus volumetric definitions
mFollow up: Not applicable
Results
CTV longitudinal margin: 3 cm (reducible to compartment boundaries)
CTV radial margin: 1.5 cm (reducible at intact fascial barriers, bone, or skin surface)
GTV delineation: MRI T1 post-contrast; fusion with CT planning images recommended
Key exception: CTV does not need to cross intact fascial planes, bone cortex, or skin
CTV radial margin: 1.5 cm (reducible at intact fascial barriers, bone, or skin surface)
GTV delineation: MRI T1 post-contrast; fusion with CT planning images recommended
Key exception: CTV does not need to cross intact fascial planes, bone cortex, or skin
Adverse events
Applicability: N/A (contouring guidelines paper)
Referenced in contouring decisions: Wound complications (lower extremity more vulnerable); pathologic fracture risk with bone involvement
Referenced in contouring decisions: Wound complications (lower extremity more vulnerable); pathologic fracture risk with bone involvement
Conclusions
A standardized RTOG atlas for GTV/CTV delineation in preoperative RT for extremity STS was developed, with 3 cm longitudinal and 1.5 cm radial CTV margins from GTV as the consensus standard, respecting natural anatomic barriers.
Key Limitations
Expert consensus document, not prospective evidence; margins derived from pattern-of-failure data and clinical judgment rather than randomized comparison. Applies specifically to extremity STS; not validated for retroperitoneal or other anatomic sites. Predates routine functional imaging and adaptive replanning.
Clinical Context
Widely adopted reference for target delineation in extremity STS RT and the basis for contouring in cooperative-group protocols. Standardized margins reduce inter-observer variability and underpin modern conformal/IMRT planning. Complements outcome trials (e.g., O'Sullivan pre-op vs post-op RT) by defining the volumes those treatments target.