Risk factors for pathologic fracture following stereotactic body radiotherapy for spinal metastases

Friday, May 3, 2024

2:15 PM – 2:19 PM CT

Location: S401ab

Presenting Author(s)

Juliana C. Capp, MD (she/her/hers)

Neurosurgery Resident
Mayo Clinic
Rochester, MN, US

Co-Author(s)

Mohamad Bydon, MD, FAANS

Professor of Neurosurgery
Mayo Clinic
Rochester, MN, US
MC

Michelle Clarke, MD

Professor of Neurosurgery
Department of Neurologic Surgery, Mayo Clinic, Rochester, MN 55902, USA
Rochester, Minnesota, United States
Benjamin Elder, MD, PhD

Neurosurgeon
Mayo Clinic
Rochester, MN, US
JF

Jeremy Fogelson, MD

Associate Professor
Mayo Clinic Department of Neurologic Surgery
Rochester, Minnesota, United States
BF

Brett Freedman, MD

Professor
Mayo Clinic, Department of Orthopaedic Surgery, United States
AH

Abdelrahman M. Hamouda, MBBCh

Research Assistant
Mayo Clinic, Department of Neurologic Surgery, United States
MK

Mohammed Karim, MD

Surgeon
Mayo Clinic, United States
RK

Roman Kowalchuk, MD

Radiation Oncologist
Mayo Clinic, United States
WK

William Krauss, MD

Neurosurgeon
Mayo Clinic
Rochester, Minnesota, United States
Nikita Lakomkin, MD

Resident
Mayo Clinic Department of Neurologic Surgery
Rochester, MN, US
KM

Kenneth Merrell, MD

Radiation Oncologist
Mayo Clinic, United States
Anthony L. Mikula, MD

Resident
Mayo Clinic Department of Neurologic Surgery
Rochester, MN, US
AN

Ahmad N. Nassr, MD

Professor
Mayo Clinic, Department of Orthopaedic Surgery, United States
Zachary Pennington, MD

Resident
Mayo Clinic Department of Neurologic Surgery
Rochester, MN, US
PR

Peter Rose, MD

Professor
Mayo Clinic Rochester
Sayreville, New Jersey, United States
AS

Arjun S. Sebastian, MD

Professor
Mayo Clinic, Department of Orthopaedic Surgery, United States

Disclosure(s):

Juliana C. Capp, MD: No financial relationships to disclose

Zachary Pennington, MD: No financial relationships to disclose

Introduction: To determine independent risk factors for vertebral compression fracture (VCF) following stereotactic body radiation therapy (SBRT) for metastatic spine disease.

Methods: Patients treated with SBRT spine metastasis at a single tertiary care center between 2008 and 2019 were retrospectively identified. Those with CT scans obtained within one year of SBRT completion were included. Variables collected included demographics, Spine Instability Neoplastic Score (SINS), primary tumor pathology, Weinstein-Boriani-Biagini (WBB) classification, chemoradiation treatment details, and bone quality as assessed by Hounsfield units (HU) on CT. HU were measured for the medullary bone of the metastatic level, the tumor, and the vertebral bodies cephalad and caudad to the metastasis. Multivariable logistic regression was used to identify predictors of post-SBRT pathologic fracture.

Results: A total of 292 patients (mean age 66 yr) with 392 unique lesions were included. The most common pathologies were prostate (n=193), kidney/renal cell (n=46), and lung (n=33). The most common tumor levels were thoracic (n=206 lesions) and lumbar (128 lesions). Of the 392 lesions, 73 suffered VCF – 21 with < 25% height loss (29%), 15 with 25-40% height loss (21%), and 37 with >40% height loss (51%). On univariate analysis, patients with VCF had lower average HU (156±52 vs 202±89; p< 0.001), more WBB sectors involved (3.3±1.5 vs. 2.5±1.3; p< 0.001), higher SINS (7.5±2.6 vs 6.1±2.2; p< 0.001), and higher average radiation dose (2621±851 vs. 2371±640 cGy; p=0.02). They were also more commonly female (33 vs 22%; p=0.05) and more commonly had non-prostate pathology (67% vs 47%; p=0.003). On multivariable logistic regression, independently significant predictors of VCF were HU≤229 (OR=6.4; p< 0.001), affected level ≥3 WBB segments (OR=2.7; p< 0.001), and SINS≥8 (OR=2.1; p=0.02).

Conclusion : Low preradiation HU, involvement of more WBB sectors, and higher SINS score were independent predictors of VCF following SBRT for metastatic spine disease.