ESTRO 2025 - Abstract Book

S1490

Clinical – Mixed sites & palliation

ESTRO 2025

Conclusion: Patients with SBM after surgery have widely varying prognoses, often overestimated by clinicians. Here, we propose an easy to use prognostic score to aid in clinical decision making and dose prescription for these patients. Patients with a poor prognostic score (2 or 3 risk factors) and no pain after surgery are unlikely to benefit from postoperative RT.

Keywords: palliative radiotherapy, spinal surgery

1414

Digital Poster PERSONAL - Personalized extended-interval fractionated SBRT using online adaptive planning: enhancing efficacy and tolerability in metastatic patients Alessandra Castelluccia 1,2 , Giuseppina Chiarello 2 , Domenico Marchesano 2 , Gianmarco Grimaldi 2 , Ivan Annessi 2 , Federico Bianciardi 2 , Annamaria Dipalma 2 , Maria Valentino 2 , Laura Verna 2 , Veronica Confaloni 3 , Martina Giraffa 3 , Federica Rea 3 , PierCarlo Gentile 2,3 1 Radiation Oncology, Perrino Hospital, Brindisi, Italy. 2 Radiation Oncology, San Pietro FBF, Rome, Italy. 3 Radiation Oncology, UPMC San Pietro FBF, Rome, Italy Purpose/Objective: Current research emphasizes the need for individualized fractionation schedules for Stereotactic Body Radiotherapy (SBRT), integrating patient factors and the biological behavior of specific tumors. This study aimed to evaluate the tolerability and efficacy of delivering personalized high-dose RT with extended fractionation interval using stereotactic technique and online adaptive planning for extracranial lesions in metastatic patients. Material/Methods: A retrospective observational analysis was conducted on 85 patients (mean age: 73 years), treated between January 2020 and September 2023. Both untreated patients and those receiving re-irradiation were included, mainly with palliative intent. Patients underwent SBRT, consisting of a weekly fraction of 10 Gy, repeated for a minimum of 2 sessions. The total dose was personalized based on tumor size and proximity to organs at risk, and further customized according to age, comorbidity, symptomatology. A daily online adaptive planning was assured. Primary endpoints included patient-reported symptom relief and the incidence of acute and late treatment-related toxicities, graded using the Common Terminology Criteria for Adverse Events (CTCAE v5.2). Secondary endpoint was local control, assessed using the Kaplan-Meier method. Results: The analysis included 102 metastases: 41 untreated sites and 61 retreatments. Median total dose was 40Gy, median fraction number was 4 (range: 2-6) and median overall treatment time was 22 days. BED10 values ranged from 40Gy to 120 Gy. Treatment sites were primarily thorax (33%), prostate (20.4%) and rectum (10.7%). The PTV was > 50cc in 47% of RT plans (range: 2,88 cc- 1756,7 cc). Mean follow-up time was 11 months. Symptomatic relief was achieved in 84.5% of patients, with complete symptom resolution in 66% and partial relief in 44%. Acute toxicity of grade 2 or higher occurred in 4.9% of patients, while late toxicity of grade 2 was observed in 1% of patients with no toxicities above grade 3 reported (Figure 1). The 12-months local control rate was 95% (figure 2).