ESTRO 2024 - Abstract Book

S1964

Clinical - Mixed sites, palliation

ESTRO 2024

2183

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Relationship between Radiation Dose and Neurologic Complications of SBRT in Spinal Metastatic Cancer

Soon Woo Hong, Jin Ho Kim

Seoul National University Hospital, Radiation Oncology, Seoul, Korea, Republic of

Purpose/Objective:

Neurological toxicity of stereotactic ablative radiotherapy (SABR) for the spine has been focused on radiation myelitis(RM). We analyzed radiation-induced radiculoplexopathy(RIRP) in patients who underwent SABR for spinal metastases.

Material/Methods:

Patients were included for the analysis who received SABR for metastatic spine tumors arising in C1 to T1 and T12 to S2 vertebrae from 2013 to 2023. Medical records and images were retrospectively reviewed. RIRP was defined as a motor power decrease by grade 2 or greater in the myotome of the spinal level treated by SABR without evidence of local progression, RM or radiation-induced cauda equina syndrome. Each neural foramen that are covered by, or adjacent to the treatment area were defined as organ at risk for dosimetric analysis. While 277 neural foramina were contoured, only structures with maximum EQD22 dose over 45Gy were included in the analysis. Cox proportional hazard model was used to identify risk factors for RIRP.

Results:

From 2013 to 2023, 156 metastatic C1-T1 and T12 to S3 spine segments in 117 patients were treated with SABR. The median follow-up was 9.25 months. Twenty-three (14.7%) local recurrences occurred. No cases of radiation myelitis were observed, and a single case of radiation-induced cauda equina syndrome was identified (0.7%). Twelve cases of RIRP (11.0%) were observed and. The planning target volume (PTV) of the treatment area and maximum point dose (0.03cm2) for each neural foramen at risk were significantly associated with the occurrence of RIRP(P<0.001).