SURG-28. KYPHO-IORT: A NEW TREATMENT PARADIGM FOR PATHOLOGICAL FRACTURES

Abstract

OBJECTIVE

This is a prospective single institution study to assess the safety and efficacy of Kypho-intraoperative radiation therapy (Kypho-IORT) for potentially mechanically unstable metastatic disease to the spine in reducing pain.

METHODS

Patients with symptomatic osteolytic vertebral body metastasis underwent Kypho-IORT: kyphoplasty procedures and intraoperative radiotherapy with the ZEISS INTRABEAM System followed by cement augmentation. Tumors were limited to vertebral body using the International Spine Radiosurgery Consortium (ISRC) anatomic classification system, SINS scores of 7-12 (potentially unstable), and Bilsky grade 0. Intraoperative CT delineation of gross tumor volume, needle applicator tip, and OAR delineation were done with deformable image registration, integrating pre-operative CT and MRI images. 10 Gy was prescribed to a distance from the source tip to the distal boundary. The prescription was limited by a maximum dose limit to the spinal cord of 12 Gy. Preoperative and postoperative pain scores were assessed with the numerical rating pain scale (NRPS). The involved spine will be imaged at 3-month intervals up to one year.

RESULTS

7 vertebral levels were treated. All patients were discharged home within 12 hours of the Kypho-IORT procedure. There was a statistically significant reduction in patient reported NPRS scores from preoperative baseline within 2 weeks (6.57 ± 2.82 preoperative versus 4.00 ± 2.16 postoperatively; p=0.0349). After 3 months, one patient with metastatic rectal cancer suffered local progression. No patients experience neurological deterioration postoperatively.

CONCLUSIONS

Kypho-IORT is a safe treatment option for potentially unstable spinal metastases. Patient reported pain scores significantly improve within two weeks, enhancing the patient's quality of life. Long-term follow up is necessary to further evaluate efficacy.