Outcome and toxicity of hypofractionated image-guided SABR for spinal oligometastases

Charlotte Billiet; Ines Joye; Carole Mercier; Lieselotte Depuydt; Geert De Kerf; Peter Vermeulen; Steven Van Laere; Erik Van de Kelft; Paul Meijnders; Dirk Verellen; Piet Dirix

doi:10.1016/j.ctro.2020.06.011

Outcome and toxicity of hypofractionated image-guided SABR for spinal oligometastases

Clin Transl Radiat Oncol. 2020 Jun 25:24:65-70. doi: 10.1016/j.ctro.2020.06.011. eCollection 2020 Sep.

Authors

Charlotte Billiet^{1

2}, Ines Joye^{1

2}, Carole Mercier^{1

2}, Lieselotte Depuydt¹, Geert De Kerf¹, Peter Vermeulen^{2

3}, Steven Van Laere^{2

3}, Erik Van de Kelft^{4

2}, Paul Meijnders^{1

2}, Dirk Verellen^{1

2}, Piet Dirix^{1

2}

Affiliations

¹ Department of Radiation Oncology, Iridium Kankernetwerk, Wilrijk (Antwerp), Belgium.
² University of Antwerp, Faculty of Medicine and Health Sciences, Campus Drie Eiken, Building S, Universiteitsplein 1, 2610 Wilrijk-Antwerp, Belgium.
³ Oncologisch Centrum GZA, Translation Cancer Research Unit, Antwerp, Belgium.
⁴ Department of Neurosurgery, Gen Hospital Nikolaas, Sint-Niklaas, Belgium.

Abstract

Background: To investigate progression free survival (PFS), local control (LC) and overall survival (OS) outcomes for patients treated with spine hypofractionated stereotactic ablative radiotherapy (SABR) and to evaluate possible predictors of rapid progression in view of a correct patient selection for this potentially curative SABR.

Materials and methods: A cohort of 59 patients with spinal metastases were treated with SABR. Patient selection criteria were the following: histologically proven diagnosis of a solid tumor, a World Health Organization (WHO) score ≤ 2, life expectancy > 6 months, Spinal Instability Neoplastic Score (SINS) ≤ 12 points and presenting with radically treated oligometastatic disease (≤5 lesions) or stable polymetastatic disease with an oligoprogressive lesion.

Results: From March 2015 to June 2019, 59 patients were treated with Linac-based SABR to 64 spinal metastases with a median follow-up of 55 months. SABR was standard delivered every other day in 3 to 10 fractions with median prescription dose of 27 Gy (range 21-49 Gy).The 1-,2- and 5-year PFS was 98%, 85% and 75% for all patients. OS at 5 years for all patients was 92%. Metachronous lesions (p < 0.01; HR = 7.1) and oligometastatic (vs. oligoprogressive) lesions (p = 0.02; HR = 0.3) were associated with higher PFS in uni- and multivariate Cox regression analysis. No significant predictors in multivariate analysis were demonstrated for rapid progressors.Vertebral compression fractures developed de novo in 6.3% (4/64) of cases. The median time to fracture was 11 months (range 7-15) after treatment. No other adverse events ≥ 3 grade were observed.

Conclusions: Tumor control and toxicity after high-dose hypofractionated SABR was evaluated in patients with spinal oligometastases. High rates of efficacy and minimal toxicity were demonstrated. Oligometastatic patients with metachronous spinal metastases seem to benefit the most from SABR.

Keywords: Outcome; SABR; Spinal metastases; Toxicity.