S917
Clinical - Mixed sites & palliation
ESTRO 2026
Patients with metastatic spinal lesions from lung cancer who received SSRS (either 16 Gy in a single fraction or 24 Gy in three fractions) across two phase II randomized trials were retrospectively analyzed. Fine– Gray subdistribution hazard models were applied to identify predictors for VCF. Overall survival (OS) was estimated by the Kaplan–Meier method, while the cumulative incidence of any-grade VCF (CIVCF) was evaluated using competing risk analysis. Results: A total of 144 patients (228 spinal segments) were included. The majority of treated sites were thoracic (n=128), followed by lumbar (n=64), cervical (n=19), and sacral (n=17) levels. Adenocarcinoma accounted for 90% of cases. Median follow-up was 54.4 months (interquartile range, 27.8–80.9 months). The 6-, 12-, and 24-month OS rates were 91.6%, 78.1%, and 54.9%, respectively. Per spinal segment, the 6-, 12-, and 24- month CIVCF were 2.6%, 7.1%, and 14.1%. Four patients developed grade ≥ 3 VCF requiring surgical intervention. Univariate analyses identified lytic lesions, ≥ 50% vertebral body involvement, paraspinal extension, baseline Bilsky score, and multifractionation as significant predictors. In the multivariate model, only ≥ 50% vertebral body involvement (sHR=2.34, 95% CI, 1.15–4.74, p=0.02) and multifractionation (sHR=2.09, 95% CI, 1.02–4.26, p=0.04) remained independently associated with VCF. Of the 144 patients, 95 were analyzed for ERCC1 (rs11615), ERCC2 (rs238406), CEP128 (rs17111237), and APOE genotypes. In the univariate analysis, no significant association was observed between these genetic variants and VCF. Conclusion: Extensive vertebral body involvement ( ≥ 50%) and multifraction SSRS independently predict post- treatment VCF in lung cancer patients. These findings underscore the importance of integrating radiographic and treatment parameters into individualized risk assessment to guide safer spinal stereotactic treatment planning. References: 1. Lai SF, Chen YL, Xiao FR, Chen YF, Lu SH, Hsu FM. Single versus multiple fraction stereotactic spine radiosurgery for spinal metastases: a prospective randomized Phase II trial. Spine J. 2025;25(7):1360- 1370. doi:10.1016/j.spinee.2025.01.0192. Chen YL, Lai SF, Yang WC, et al. Elective versus Involved Target Volume Definition of Stereotactic Spine Radiosurgery for Spinal Metastases: A Phase 2 Randomized Clinical Trial. Neuro Oncol. Published online October 27, 2025. doi:10.1093/neuonc/noaf254 Keywords: spine radiosurgery, vertebral fracture
recurrence/progression of brain metastases after initial SRT is a feasible and well tolerated approach for carefully selected patients. The role of an accurate multidisciplinary evaluation and patients’ selection is fundamental. Further prospective data are needed to evaluate efficacy and prognostic factors. References: 1. Kotecha R, La Rosa A, Brown PD, et al. Multidisciplinary management strategies for recurrent brain metastasis after prior radiotherapy: An overview. Neuro Oncol. 2025;27(3):597-615. doi:10.1093/neuonc/noae2202. Minniti G, Scaringi C, Paolini S, et al. Repeated stereotactic radiosurgery for patients with progressive brain metastases. J Neurooncol. 2016;126(1):91-97. doi:10.1007/s11060- 015-1937-43. Kowalchuk RO, Niranjan A, Lee CC, et al. Reirradiation With Stereotactic Radiosurgery After Local or Marginal Recurrence of Brain Metastases From Previous Radiosurgery. Int J Radiat Oncol Biol Phys. 2022;112(3):726-734. doi:10.1016/j.ijrobp.2021.10.008 Keywords: Brain metastases, reirradiation, radiosurgery Risk Factors for Vertebral Fracture Following Spine Stereotactic Radiosurgery in Lung Cancer: A Pooled Post Hoc Analysis of Two Phase II Trials Yi-Lun Chen 1,2 , Shih-Fan Lai 3,2 , Wen-Chi Yang 3,2 , Shao- Lun Lu 3,2 , Fon-Yih Tsuang 4 , Fu-Ren Xiao 4 , Wei-Hsin Lin 5 , Ya-Fang Chen 6 , Feng-Ming Hsu 3,2 1 Department of Oncology, National Taiwan University Biomedical Park Hospital, Hsinchu, Taiwan. 2 Department of Oncology, National Taiwan University Hospital, Taipei, Taiwan. 3 Department of Radiation Oncology, National Taiwan University Cancer Center, Taipei, Taiwan. 4 Department of Surgery, National Taiwan University Hospital, Taipei, Taiwan. 5 Department of Orthopaedic Surgery, National Taiwan University Hospital, Taipei, Taiwan. 6 Department of Medical Imaging, National Taiwan University Hospital, Taipei, Taiwan Purpose/Objective: Vertebral compression fracture (VCF) is a clinically relevant adverse event following stereotactic spine radiosurgery (SSRS). Yet, predictive factors for VCF specifically in patients with lung cancer remain insufficiently characterized. This post hoc pooled analysis of two phase II randomized studies aimed to delineate clinical predictors associated with VCF occurrence in this population. Material/Methods: Mini-Oral 4434
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