S866
Clinical - Mixed sites & palliation
ESTRO 2026
Palliative Radiotherapy Endpoints for Bone Metastases Trials: Updated Recommendations (2025). Radiother Oncol. 2025;190:110659.3.Rades D, Chow E, Schild SE. Radiotherapy for bone metastases: principles, techniques, and clinical outcomes. Cancer Treat Rev. 2022;102:102329. Keywords: palliative efficacy, soft-tissue metastases
patients with symptomatic NSBM showing radiologic or clinical soft-tissue extension and no prior irradiation to the index site were included. Eighteen patients received 24 Gy/6 fractions and 13 received 0–7–21 regimen. Pain and analgesic use were assessed using Brief Pain Inventory–Short Form (BPI-SF). The primary objective was symptom control (pain relief and reduced analgesic use) and tumour/soft-tissue response per RECIST criteria. Secondary objectives were toxicity (graded by RTOG) and in-field progression-free survival (PFS) from treatment completion to progression or death. Results:
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Patient-Based Dosimetric and Outcome Analysis of Photon GRID Radiotherapy: Insights from a Large Institutional Experience Kaidi Wang 1 , Pouya Sabouri 2 , Renteng Hou 2 , Eric R Siegel 3 , Robert J Griffin 2 , Fen Xia 2 1 Department of Radiation Oncology, The Ohio State University, Columbus, USA. 2 Department of Radiation Oncology, University of Arkansas for Medical Sciences, Little Rock, USA. 3 Department of Biostatistics, University of Arkansas for Medical Sciences, Little Rock, USA Purpose/Objective: GRID radiotherapy (GRID RT) is an emerging approach for bulky tumors. While prior work focused on simulated dosimetry, real-world patient data remain limited. Our study is one of the first and largest reports based on actual patient-generated GRID plans, incorporating both dosimetric analyses and survival correlations.
Mean age was 49.4 ± 9.6 years (range 25–76). Breast cancer was the most common primary (41.9%), followed by prostate (29%). Pelvis was the most frequent site (36.3%). Median soft-tissue lesion volume was 64 cc (range 28–138 cc) and maximal dimension 5.4 cm (range 2.7–22 cm). Median follow-up was 9.5 months.Complete symptom control occurred in 53.8% (0–7–21) vs 55.6% (24 Gy/6) (p = 0.93); partial response in 38.5% vs 33.3% (p = 0.76). No pain progression was reported at 3 months.Mass reduction occurred more often with 0–7–21 (69.2%) than 24 Gy/6 (61.1%) (p = 0.64). Mean reduction was 59.0 ± 20.0% vs 58.6 ± 17.5% (p = 0.96).Grade 2 dermatitis occurred in 38.5% (0–7–21) vs 22.2% (24 Gy/6); one patient (5.6%) in the latter developed grade 3 toxicity (p = 0.70).Six-month in-field PFS was 84.6% (0–7–21) vs 77.8% (24 Gy/6) (p = 0.65). Conclusion: The 0-7-21 is an effective and well-tolerated palliative RT regimen for NSBM with soft-tissue involvement. Larger, prospective studies are needed to confirm these outcomes. References: 1.Oldenburger E, et al. Response assessment and endpoint definitions in palliative radiotherapy for bone metastases: ESTRO consensus update. Radiother Oncol. 2023;182:109479.2.Chow E, Hoskin P, Mitera G, Zeng L, Lutz S, Roos D. International Consensus on
Material/Methods: We retrospectively analyzed GRID RT plans for 44 patients treated at our institution. Dose metrics including peak-to-valley dose ratio (PVDR), peak-to- peak distance (p-p), peak width (defined as full width at half maximum), D10%/D90% and DVH indices (D5%, D10%, D20%, D50%, D90%) were extracted. Dosimetric parameters were evaluated in relation to previously
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