ESTRO 2025 - Abstract Book

S1458

Clinical – Mixed sites & palliation

ESTRO 2025

Results: Among the included cases, 68.7% and 42.6% had soft tissue involvement and movement exceeding 1 mm, respectively. The median follow-up duration for local recurrence was 11.6 (range: 0.7 – 44.9) months, whereas the median duration to local recurrence was 6.3 months. Within 12 months, 29.3% of the patients experienced local recurrence, among whom 43.9% moved ≥ 1 mm during treatment, whereas 15.8% did not move. Univariable analysis found that both soft tissue involvement (OR = 10.3, 1.21 –87.9; p= 0.033) and patient movement ≥ 1 mm (OR = 5.75, 1.45 – 22.8; p = 0.013) were associated with local recurrence. Multivariable analysis identified patient movement as an independent prognostic factor for local recurrence (OR = 5.15, 1.06 – 25.0; p = 0.042). Conclusion: Our results suggest that patient movement during spinal SBRT was associated with local recurrence, emphasizing the need for better immobilization techniques and shorter delivery times to improve tumor control.

Keywords: SBRT, Local recurrence, Patient movement

References: Shimizu H, Koide Y, Haimoto S, et al. Frequency of and risk factors associated with local recurrence after spinal stereotactic body radiation therapy without surgery. J Neurooncol. 2024;169(3):563-570. doi: 10.1007/s11060-024 04755-7.

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Digital Poster Proton beam therapy in cancer treatment: a systematic review of randomised trials Chia Ching Lee Radiation Oncology, National University Cancer Institute Singapore, Singapore, Singapore

Purpose/Objective: Evidence supporting proton beam therapy (PBT) in cancer treatment is emerging. This study aimed to summarize randomised controlled trials (RCTs) evaluating PBT in terms of efficacy and toxicity outcomes. Material/Methods: A search was conducted through scientific databases to identify eligible studies comparing PBT with standard treatment in any malignancy. We assessed the risk of bias of each trial using the revised Cochrane tool (RoB 2.0). The outcomes of interest were efficacy and toxicity. We employed Synthesis Without Meta-analysis (SWiM) approach to summarize the data qualitatively. Results: Ten RCTs (1,636 patients) with low risk of bias were included, covering a range of malignancies. PBT reduced toxicity in glioblastoma, oesophageal, and oropharyngeal cancers while maintaining comparable survival outcomes compared to intensity-modulated radiation therapy (IMRT). In breast cancer, proton postmastectomy radiation therapy (RT) improved tissue sparing, and hypofractionation demonstrated comparable disease control. Proton craniospinal irradiation improved overall survival (OS) and central nervous system progression-free survival (PFS) in leptomeningeal metastases without increasing severe adverse events, compared to involved-field photon radiation therapy. For hepatocellular carcinoma, PBT reduced treatment burden and costs compared to trans-arterial chemoembolization. However, for NSCLC, passive scattering proton therapy did not improve lung dose-volume indices and radiation pneumonitis with no difference in local failure compared with IMRT. In prostate cancer, PBT showed no advantage over IMRT in quality of life or PFS. In sacrococcygeal chordoma, PBT and carbon ion therapy demonstrated comparable OS and local PFS.