Stereotactic Body Radiation Therapy for Spinal Metastasis Using Biaxially Rotational Dynamic Radiation Therapy...

Area of Science:

• Radiation Oncology
• Medical Physics

Background:

• Stereotactic body radiation therapy (SBRT) is an advanced cancer treatment.
• Non-coplanar volumetric-modulated arc therapy (VMAT) techniques aim to improve treatment accuracy.
• Biaxially rotational dynamic radiation therapy (BROAD-RT) is a novel non-coplanar VMAT technique.

Purpose of the Study:

• To evaluate the clinical outcomes of spine SBRT using the novel BROAD-RT technique.
• To assess the feasibility, accuracy, and toxicity of BROAD-RT for spine SBRT.
• To investigate the efficacy of a 27 Gy in 3 fractions dose regimen delivered via BROAD-RT.

Main Methods:

• Retrospective analysis of 13 patients undergoing spine SBRT with BROAD-RT.
• Prospective feasibility study conducted from August 2020 to April 2022.
• Dosimetric quality assurance (QA) performed using ArcCHECK for each patient.

Main Results:

• Median patient age was 73; common primary cancers included prostate, lung, breast, liver, and thyroid.
• 84.6% of patients had oligo-metastatic disease at the time of SBRT.
• One-year local control (LC) and overall survival (OS) were 84.6% and 100%; three-year rates were 59.8% and 68.4%.
• Cumulative incidence of grade ≥2 vertebral compression fracture (VCF) was 7.7% at 1 year and 23.1% at 3 years.
• No grade ≥3 toxicities or radiation-induced myelopathies were observed, apart from VCF.

Conclusions:

• BROAD-RT facilitates accurate non-coplanar VMAT for spine SBRT without couch rotation.
• The 27 Gy in 3 fractions dose yielded acceptable toxicity.
• Further research is needed to optimize dose and fractionation strategies for spine SBRT using BROAD-RT.