Introduction: Open surgery or kyphplasty followed by external irradiation is the standard of care for patients with unstable spine metastasis. Radiation induced vertebral compression fractures range from 11-39%. Radiation is typically palliative due to the systemic tumor burden; therefore, pain control and improvement of quality of life is paramount. Kypho-IORT is a minimally invasive procedure to radiate metastasis and prevent compression fractures while providing immediate pain relief in potentially unstable spines. Due to rapid fall off, higher doses of radiation can be administered to the tumor bed while limiting spinal cord toxicity, when compared to stereotactic body radiation therapy (SBRT).
Methods: Enrolled patients met the following criteria: known primary histology, potentially unstable spine (SINS score 7-12), and low Bilksy grade (0). Pre and postoperative pain scores were assessed.
Procedure: The involved vertebral body is accessed percutaneously via its pedicles (a). A metallic sleeve is placed and intraoperative CT was utilized to confirm proper placement within the tumor via the pedicle (d). An introducer is placed within the sleeve and INTRABEAM radiation system (Carl Zeiss Surgical, Oberkochen, Germany) is guided down the sleeve into the tumor bed (c). 10Gy to tumor margins is delivered (radiological biological effective (RBE) Dose = 14 Gy) (e). The spinal cord dose is limited to RBE Dose = 12Gy. Kyphoplasty of the vertebral body is then completed, with the ability to restore vertebral body height when appropriate (b).
Results: 7 vertebral levels were treated, with mean SINS score of 8.6±1.9. All patients were discharged home within 12 hours of Kypho-IORT. There was a statistically significant reduction in patient reported NPRS scores from preoperative baseline within 2 weeks (6.57±1.4 preoperative versus 3.57±2.57 postoperatively; p=0.0189). All patients remained neurologically stable postoperatively.
Conclusions: Kypho-IORT is a safe treatment option for metastases in a potentially unstable spine. Patient reported pain scores significantly improve within two weeks, increasing patients quality of life with a palliative treatment that allows same day return to home. Long-term follow up is necessary to further evaluate local control and fracture rates.
Patient Care: Conventional spinal SRS for metastatic disease as has a high rate of vertebral body fractures. With Kypho-IORT, pain scores improve within 1 week and fracture rates may be reduced.
Learning Objectives: 1) Understand the utility of Kypho-IORT in the treatment of spine metastasis. 2) Be able to counsel patients appropriately on the option of Kypho-IORT in the settle of spine metastatic disease with vertebral body fractures.