Spine Stereotactic Body Radiotherapy to Three or More Contiguous Vertebral Levels

Khaled Dibs; Dukagjin M Blakaj; Rahul N Prasad; Alexander Olausson; Eric C Bourekas; Daniel Boulter; Ahmet S Ayan; Eric Cochran; William S Marras; Prasath Mageswaran; Evan Thomas; Hyeri Lee; John Grecula; Raju R Raval; Ehud Mendel; Thomas Scharschmidt; Russell Lonser; Arnab Chakravarti; James B Elder; Joshua D Palmer

doi:10.3389/fonc.2022.912804

Spine Stereotactic Body Radiotherapy to Three or More Contiguous Vertebral Levels

Front Oncol. 2022 Jun 8:12:912804. doi: 10.3389/fonc.2022.912804. eCollection 2022.

Authors

Khaled Dibs¹, Dukagjin M Blakaj¹, Rahul N Prasad¹, Alexander Olausson¹, Eric C Bourekas², Daniel Boulter², Ahmet S Ayan¹, Eric Cochran¹, William S Marras³, Prasath Mageswaran³, Evan Thomas¹, Hyeri Lee¹, John Grecula¹, Raju R Raval¹, Ehud Mendel⁴, Thomas Scharschmidt⁵, Russell Lonser⁶, Arnab Chakravarti⁴, James B Elder⁶, Joshua D Palmer¹

Affiliations

¹ Department of Radiation Oncology, The James Cancer Hospital at the Ohio State University Wexner Medical Center, Columbus, OH, United States.
² Department of Radiology, The James Cancer Hospital at the Ohio State University Wexner Medical Center, Columbus, OH, United States.
³ Spine Research Institute, Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, OH, United States.
⁴ Department of Neurosurgery, Yale University School of Medicine, New Haven, CT, United States.
⁵ Department of Orthopedic Surgery, The James Cancer Hospital at the Ohio State University Wexner Medical Center, Columbus, GA, United States.
⁶ Department of Neurosurgery, The James Cancer Hospital at the Ohio State University Wexner Medical Center, Columbus, GA, United States.

Abstract

Background: With survival improving in many metastatic malignancies, spine metastases have increasingly become a source of significant morbidity; achieving durable local control (LC) is critical. Stereotactic body radiotherapy (SBRT) may offer improved LC and/or symptom palliation. However, due to setup concerns, SBRT is infrequently offered to patients with ≥3 contiguous involved levels. Because data are limited, we sought to evaluate the feasibility, toxicity, and cancer control outcomes of spine SBRT delivered to ≥3 contiguous levels.

Methods: We retrospectively identified all SBRT courses delivered between 2013 and 2019 at a tertiary care institution for postoperative or intact spine metastases. Radiotherapy was delivered to 14-35 Gy in 1-5 fractions. Patients were stratified by whether they received SBRT to 1-2 or ≥3 contiguous levels. The primary endpoint was 1-year LC and was compared between groups. Factors associated with increased likelihood of local failure (LF) were explored. Acute and chronic toxicity was assessed. In-depth dosimetric data were collected.

Results: Overall, 165 patients with 194 SBRT courses were identified [54% were men, median age was 61 years, 93% had Karnofsky Performance Status (KPS) ≥70, and median follow-up was 15 months]. One hundred thirteen patients (68%) received treatment to 1-2 and 52 to 3-7 (32%) levels. The 1-year LC was 88% (89% for 1-2 levels vs. 84% for ≥3 levels, p = 0.747). On multivariate analysis, uncontrolled systemic disease was associated with inferior LC for patients with ≥3 treated levels. No other demographic, disease, treatment, or dosimetric variables achieved significance. Rates of new/progressive fracture were equivalent (8% vs. 9.5%, p = 0.839). There were no radiation-induced myelopathy or grade 3+ acute or late toxicities in either group. Coverage of ≥95% of the planning target volume with ≥95% prescription dose was similar between groups (96% 1-2 levels vs. 89% ≥3 levels, p = 0.078).

Conclusions: For patients with ≥3 contiguous involved levels, spine SBRT is feasible and may offer excellent LC without significant toxicity. Prospective evaluation is warranted.

Keywords: local control; multilevel; postoperative; radiosurgery; spine metastases; stereotactic body radiation therapy; stereotactic radiotherapy; toxicity.