S895
Clinical - Mixed sites & palliation
ESTRO 2026
prostate (28.9%), and lung (15.8%). At the time of SBRT, 53.5% of patients had oligometastatic disease, and 68.4% had bone-only metastases. The median prescribed dose was 30 Gy in 5 fractions. Dose escalation as 35-40 Gy, either to the whole vertebral segment or to the gross lesion only, was performed to 34% of lesions. At a median follow-up of 19 months (range, 6–113 months), the local control (LC) rate was 90.8%. Median OS was 43 months, with 1- and 2-year OS rates of 88.8% and 65%, respectively. On multivariate analysis, young age ( ≤ 59 years, p = 0.033), breast or prostate primary (p = 0.001), and absence of visceral metastases (p = 0.031) were independent favorable prognostic factors for OS. Median local progression-free survival (LPFS) was 36.3 months, with 1- and 2-year LPFS rates of 86.7% and 59.9%, respectively. Age (p = 0.047) and primary tumor histology (p < 0.001) were independent predictors for LPFS. No significant difference in outcomes was observed between patients receiving <35 Gy and those receiving ≥ 35 Gy in the overall cohort. However, in subgroup analysis, patients with breast cancer had superior LPFS with dose escalation (2-year 89.6% vs. 49.9%, p=0.023). No radiation-induced myelopathy was observed. Baseline vertebral compression fractures (VCFs) were identified in 13 lesions (8.5%), with progression observed in 3 following SBRT. Among lesions without baseline VCFs, only one new VCF (0.7%) developed, associated with local progression.
in FAST-01.
Conclusion: FAST-02—the second in-human proton FLASH trial and the first in the thoracic skeleton—demonstrates feasibility of delivery with minimal acute toxicity and no grade ≥ 2 treatment-related events. Together with FAST-01’s favorable experience treating extremities, these data support advancing proton FLASH research toward more complex thoracic indications. Keywords: FLASH, clinical trial, proton Five-fraction spine stereotactic body radiation therapy: practice patterns and outcomes from a single institution Ecem Yigit, Alper Kahvecioglu, Fazli Yagiz Yedekci, Sezin Yuce Sari, Melis Gultekin, Pervin Hurmuz, Gokhan Ozyigit, Mustafa Cengiz, Ferah Yildiz Department of Radiation Oncology, Hacettepe University, Ankara, Turkey Purpose/Objective: This study aimed to evaluate clinical outcomes, prognostic factors, and treatment tolerability in patients treated with 5-fraction spine stereotactic body radiation therapy (SBRT) in a single institution. Material/Methods: A total of 153 spinal metastases in 114 patients Digital Poster 3317 treated between 2014 and 2023 were retrospectively analyzed. The SBRT dose was prescribed according to the International Spine Radiosurgery Consortium Consensus guidelines. Survival outcomes were estimated using the Kaplan–Meier method, and prognostic factors were assessed with the log-rank test and multivariate Cox regression analysis. Results: The median age was 59 years (range, 23–83). The most common types of primary tumor were breast (37.7%),
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