Assessment of minimum target dose as a predictor of local failure after spine SBRT

Roman O Kowalchuk; Trey C Mullikin; Grant M Spears; Benjamin A Johnson-Tesch; Peter S Rose; Brittany L Siontis; Dong Kun Kim; Brian A Costello; Jonathan M Morris; Robert W Gao; Satomi Shiraishi; John J Lucido; Kenneth R Olivier; Dawn Owen; Bradley J Stish; Mark R Waddle; Nadia N Laack; Sean S Park; Paul D Brown; Kenneth W Merrell

doi:10.1016/j.radonc.2024.110260

Assessment of minimum target dose as a predictor of local failure after spine SBRT

Radiother Oncol. 2024 Mar 27:195:110260. doi: 10.1016/j.radonc.2024.110260. Online ahead of print.

Authors

Roman O Kowalchuk¹, Trey C Mullikin², Grant M Spears³, Benjamin A Johnson-Tesch⁴, Peter S Rose⁵, Brittany L Siontis⁶, Dong Kun Kim⁴, Brian A Costello⁶, Jonathan M Morris⁴, Robert W Gao¹, Satomi Shiraishi⁷, John J Lucido⁷, Kenneth R Olivier¹, Dawn Owen¹, Bradley J Stish¹, Mark R Waddle¹, Nadia N Laack¹, Sean S Park¹, Paul D Brown¹, Kenneth W Merrell⁸

Affiliations

¹ Mayo Clinic, Department of Radiation Oncology, Rochester, MN 55905, United States.
² Duke University, Department of Radiation Oncology, Durham, NC 27710, United States.
³ Mayo Clinic, Department of Statistics, Rochester, MN 55905, United States.
⁴ Mayo Clinic, Department of Radiology, Rochester, MN 55905, United States.
⁵ Mayo Clinic, Department of Orthopedic Surgery, Rochester, MN 55905, United States.
⁶ Mayo Clinic, Department of Medical Oncology, Rochester, MN 55905, United States.
⁷ Mayo Clinic, Department of Medical Physics, Rochester, MN 55905, United States.
⁸ Mayo Clinic, Department of Radiation Oncology, Rochester, MN 55905, United States. Electronic address: merrell.kenneth@mayo.edu.

PMID: 38548114
DOI: 10.1016/j.radonc.2024.110260

Abstract

Objectives: Metastasis-directed stereotactic body radiation therapy (SBRT) has demonstrated robust clinical benefits in carefully selected patients, improving local control and even overall survival (OS). We assess a large database to determine clinical and dosimetric predictors of local failure after spine SBRT.

Methods: Spine SBRT treatments with imaging follow-up were identified. Patients were treated with a simultaneous integrated boost technique using 1 or 3 fractions, delivering 20-24 Gy in 1 fraction to the gross tumor volume (GTV) and 16 Gy to the low dose volume (or 27-36 Gy and 21-24 Gy for 3 fraction treatments). Exclusions included: lack of imaging follow-up, proton therapy, and benign primary histologies.

Results: 522 eligible spine SBRT treatments (68 % single fraction) were identified in 377 unique patients. Patients had a median OS of 43.7 months (95 % confidence interval: 34.3-54.4). The cumulative incidence of local failure was 10.5 % (7.4-13.4) at 1 year and 16.3 % (12.6-19.9) at 2 years. Local control was maximized at 15.3 Gy minimum dose for single-fraction treatment (HR = 0.31, 95 % CI: 0.17 - 0.56, p < 0.0001) and confirmed via multivariable analyses. Cumulative incidence of local failure was 6.1 % (2.6-9.4) vs. 14.2 % (8.3-19.8) at 1 year using this cut-off, with comparable findings for minimum 14 Gy. Additionally, epidural and soft tissue involvement were predictive of local failure (HR = 1.77 and 2.30).

Conclusions: Spine SBRT offers favorable local control; however, minimum dose to the GTV has a strong association with local control. Achieving GTV minimum dose of 14-15.3 Gy with single fraction SBRT is recommended whenever possible.