S892
Clinical - Mixed sites & palliation
ESTRO 2026
Radiation Therapy (LRT). Radiat Res. 2020;194(6):737- 746. doi:10.1667/RADE-20-00066.1.Prezado Y, Grams M, Jouglar E, Martínez-Rovira I, Ortiz R, Seco J, et al. Spatially fractionated radiation therapy: a critical review on current status of clinical and preclinical studies and knowledge gaps. Phys Med Biol. 2024;69(10):10TR02. doi:10.1088/1361-6560/ad4192. Keywords: Lattice RT, SFRT, Bulky Tumors
Statistical and post-hoc analyses assessed associations between indices and clinical categories. Results: Thirty percent of patients exhibited abscopal responses with regression of non-irradiated lesions. At 6 months, 55% showed >30% tumour reduction and improved pain and global health. Most plans maintained valleys below 3 Gy, V5[CorkGTV] <10%, and V3[CorkGTV] <35%. Delivery time remained under 7 minutes. Spearman’s rank correlation between indices and response groups was positive for cork3 ( ρ =0.32) and cork5 ( ρ =0.28), consistent with the observed biological trend. Mean cork3 values increased across response groups (ABSCOPAL > With_R > Without_R), indicating that larger cold-tissue volumes per vertex were associated with a higher likelihood of systemic response (fig.1). These findings are consistent with the hypothesis of Prezado (2024) that spatial dose modulation enhances immune-mediated effects beyond target volumes. The observed abscopal frequency and these results further motivate investigation into how the extent and geometry of low- dose radiation modulate immune activation.
Digital Poster 3256 SBRT for hepatocellular carcinoma: survival outcomes and dose–response analysis Victoria Alonso Gonzalez 1 , Diego Piedrafita Suárez 2 , Johanna del Carmen Peña Vivas 1 , Laura María López Pérez 1 , Arantzazu Iglesias Agüera 1 1 Radiation Oncology, HUCA, Oviedo, Spain. 2 Medical Physics, HUCA, Oviedo, Spain Purpose/Objective: To evaluate overall survival (OS) after stereotactic body radiotherapy (SBRT) for hepatocellular carcinoma (HCC), with secondary endpoints of progression-free survival (PFS) and dose–response. We also provide an exploratory contextual comparison with historical outcomes after transarterial chemoembolization (TACE). Material/Methods: From July 2021 to April 2025, twenty consecutive patients with unresectable or recurrent HCC received SBRT. Inclusion criteria: ECOG ≤ 2, Child–Pugh A–B7, no extrahepatic disease; previous treatments (resection, TACE, RFA, systemic therapy) were allowed. Up to three lesions per patient were treated. Prescriptions were 45 Gy in 3 fractions (BED ₁₀ 112.5 Gy), 60 Gy in 6 fractions (BED ₁₀ 120 Gy), or 50 Gy in 6 fractions (BED ₁₀ 91.7 Gy). Image-guided SBRT and standard OAR dose guidance were used. Follow-up with imaging and labs occurred every 3–6 months. OS and PFS were measured from SBRT beginning. Toxicities were graded by CTCAE v5.0. Results: Median follow-up was 16 months (range 3–45). Treatment was well tolerated: no grade ≥ 2 gastrointestinal or hepatic toxicity was observed, and no cases suggestive of radiation-induced liver disease occurred. By data-lock (Nov-2025), approximately half of patients had experienced disease progression
Fig.1. Conclusion: The helical vertex geometry enabled an efficient clinical workflow. The cork3 index provided preliminary quantification of spatial dose heterogeneity and correlated with systemic responses, supporting its potential as a radiobiological biomarker. Further validation is warranted to confirm these findings and integrate them into adaptive treatment planning. References: Kim S, Kim T, Ko SJ, Serago C, Smith A, Vallow LA, et al. Negative margin technique—a novel planning strategy to improve dose conformation in SBRT using dynamic conformal arc delivery. J Appl Clin Med Phys. 2013;14(5):79–89. doi:10.1120/jacmp.v14i5.4283Wu X, Perez NC, Zheng Y, Li X, Jiang L, Amendola BE, et al. The Technical and Clinical Implementation of LATTICE
Made with FlippingBook - Share PDF online