Comparison of segment- and GTV-based target volume concepts in SBRT for vertebral metastases: a post hoc secondary analysis of two prospective clinical trials Target volume concepts in dose-escalation SBRT.

Authors

Indira Madani, Reinhart A Sweeney, Maria Hawkins, Jose Belderbos, Nicolaus Andratschke, Lotte Wilke, Merina Ahmed, Frederick Mantel, Charlotte Billiet, Susanne Rogers, Ciro Franzese, Daniel Schnell, Mateusz Spałek, Daniel M Aebersold, Hossein Hemmatazad, Thomas Zilli, Nikolaos Koutsouvelis, Judit Boda-Heggemann, Brigitta G Baumert, Jean-Jacques Stelmes, Franziska Nägler, Philipp Gut, Christian Weiß, Alessio Bruni, Frank Zimmermann, Robert Förster, Jörg Zimmer, Matthias Guckenberger

Published in

International journal of radiation oncology, biology, physics. Nov 12, 2026. Epub Nov 12, 2026.

Abstract

To compare outcome of the segment-based and gross tumor volume (GTV)-based target volume definition concepts in fractionated SBRT for vertebral metastases.
This is a post hoc secondary analysis of two prospective clinical trials conducted between 2012 and 2015 (XXX1 [segment-based concept]) and between 2016 and 2023 (XXX2 [GTV-based concept]). In both trials, fractionated SBRT for painful and non-painful mechanically stable or potentially unstable vertebral metastases delivered two dose levels using simultaneous integrated boost (SIB): 35-40 Gy/5 or 48.5 Gy/10 to the high-dose planning target volume (PTV) and 20 Gy/5 and 30 Gy/10 to the conventional-dose PTV, respectively. The high-dose PTV was defined either as segment-based (XXX1) following international guidelines or GTV-based (XXX2). The primary endpoints were freedom from local progression (FFLP) and vertebral compression fracture (VCF) assessed using the Kaplan-Meier method.
Patient characteristics showed several imbalances, in general more favorable for patients in the XXX2 group. The high-dose PTV in the XXX2 group (177 patients with 197 metastases) was significantly smaller than in the XXX1 group (57 patients with 63 metastases) (median 11 cm³ vs median 58 cm³, P<.001). At median follow-up of survivors of 24 months, 2-year FFLP and progressive and de novo VCF rates in the XXX2 and XXX1 groups were 95.3% vs. 86.4% (P<.001) and 10.1% vs. 34.6% (P<.001), respectively. No myelopathy or plexopathy were observed in either group. On univariable analysis the segment-based concept (Hazard ratio [HR] 5.21, 95% CI 2.53-10.72; P<.001) and lumbar spine location (HR 2.44, 95% CI 1.24-4.82, P=.01) were associated with higher rates of progressive and de novo VCF.
In fractionated SBRT for vertebral metastases, reduction of the high-dose PTV to the GTV combined with focal dose escalation and low-dose elective vertebral coverage did not compromise local control and lowered the rates of VCF.

PMID:
43020388
Bibliographic data and abstract were imported from PubMed on 13 Nov 2026.

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