Histologic Classifier of Radiosensitivity to Spine Stereotactic Body Radiation Therapy.

Area of Science:

• Radiation Oncology
• Spine Metastases Treatment
• Clinical Outcomes Research

Background:

• Spine stereotactic body radiation therapy (SBRT) is effective in preventing local failure (LF) compared to conventional radiotherapy.
• Limited data exist comparing different SBRT dose-fractionation schemes for LF and vertebral compression fracture (VCF) risk.

Purpose of the Study:

• To compare the efficacy and safety of different spine SBRT dose-fractionation schemes.
• To evaluate the impact of SBRT on local failure (LF) and vertebral compression fracture (VCF).

Main Methods:

• Retrospective cohort study of 1,838 patients with 2,702 de novo spine SBRT lesions (2014-2023).
• Analysis of LF (progressive disease on MRI) and VCF (progressive/new fracture on MRI without LF).
• Comparison of 24 Gy/1 fraction, 27 Gy/3 fractions, and 30 Gy/3 fractions regimens.

Main Results:

• Two-year LF rates: 7% (24 Gy/1 fx), 11% (30 Gy/3 fx), 17% (27 Gy/3 fx) (p<0.001).
• Two-year VCF rates: 10% (24 Gy/1 fx), 3% (30 Gy/3 fx), 2% (27 Gy/3 fx) (p<0.001).
• 30 Gy/3 fx showed lower LF and similar VCF requiring intervention compared to 27 Gy/3 fx. Histology impacts LF risk; surgery may benefit high-grade epidural disease.

Conclusions:

• The 30 Gy in 3 fractions SBRT regimen is preferred for spine tumors, offering superior local control with acceptable VCF risk.
• For Class B-C lesions with high-grade epidural disease, separation surgery before SBRT may enhance local control.