Top Line: Determining the ideal fractionation scheme for definitive stereotactic ablative radiation (SABR) for renal cell carcinoma (RCC) depends largely on the individual target, so let’s get into contours.
The Study: IROCK convened 16 experts to tackle target delineation. Participants contoured four tricky real-world scenarios—(1) a >10 cm tumor with IVC thrombus, (2) a central tumor abutting the renal hilum, (3) post-nephrectomy local recurrence, and (4) recurrence in an ablation cavity—plus investigational renal substructures such as cortex and hilum. Results were reassuringly concordant: median Dice Similarity Coefficient (i.e., overall overlap) was 0.85 across cases (≥0.70 for all scenarios), with median mean distance to agreement of 2.17 mm and maximum distance of 9 mm. Consensus recommendation was to always include tumor thrombus and ablation cavities in the target volume and to prioritize critical organ constraints over target coverage. A final nuance is that the ipsilateral renal cortex should be contoured as renal parenchyma minus target, renal pelvis, vasculature, and proximal ureter.
TBL: We now have first international consensus contouring guideline for RCC SABR. | Dhar, Int J Radiat Oncol Biol Phys 2026
The Study: IROCK convened 16 experts to tackle target delineation. Participants contoured four tricky real-world scenarios—(1) a >10 cm tumor with IVC thrombus, (2) a central tumor abutting the renal hilum, (3) post-nephrectomy local recurrence, and (4) recurrence in an ablation cavity—plus investigational renal substructures such as cortex and hilum. Results were reassuringly concordant: median Dice Similarity Coefficient (i.e., overall overlap) was 0.85 across cases (≥0.70 for all scenarios), with median mean distance to agreement of 2.17 mm and maximum distance of 9 mm. Consensus recommendation was to always include tumor thrombus and ablation cavities in the target volume and to prioritize critical organ constraints over target coverage. A final nuance is that the ipsilateral renal cortex should be contoured as renal parenchyma minus target, renal pelvis, vasculature, and proximal ureter.
TBL: We now have first international consensus contouring guideline for RCC SABR. | Dhar, Int J Radiat Oncol Biol Phys 2026