Main Session
Sep
28
PQA 04 - Breast Cancer, Patient Reported Outcomes/QoL/Survivorship, Functional Radiation Medicine, Hematologic Malignancies, Palliative Care, and International/Global Oncology
Presenter(s)
Soon Woo Hong, MD - Seoul National University Hospital, Seoul, Jongno-gu
S. W. Hong, and J. H. Kim; Department of Radiation Oncology, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea, Republic of (South)
Purpose/Objective(s):
Neurological toxicity of stereotactic ablative radiotherapy (SABR) for the spine has been focused on radiation myelitis(RM). We investigated radiation-induced radiculo-plexopathy(RIRP) in patients who underwent SABR for spinal metastases.Materials/Methods:
Patients were included for the analysis who received SABR for metastatic spine tumors arising in C3 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 MRC 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 is covered by or adjacent to the treatment area was defined as an organ at risk for dosimetric analysis. While 407 neural foramina were contoured, only structures with a maximum EQD22 dose over 45Gy were included in the analysis. The Cox proportional hazard model was used to identify risk factors for RIRP.Results:
From 2013 to 2023, 168 metastatic C1-T1 and T12 to S3 spine segments in 132 patients were treated with SABR. The median follow-up was 9.5 months. Twenty-four (14.3%) local recurrences occurred. No cases of radiation myelitis were observed, and a single case of radiation-induced cauda equina syndrome was identified (0.9%). Twelve cases of RIRP (9.1%) were observed. The planning target volume (PTV) of the treatment area and maximum dose for each neural foramen at risk were significantly associated with the occurrence of RIRP (p<0.001).Conclusion:
While RM or radiation-induced cauda equina syndrome rarely occurs, RIRP occurs more frequently after spinal SABR. Further studies are necessary to accurately characterize RIRP and sophisticatedly define more suitable organs at risk. Meanwhile, neural foramina may serve as surrogate organs at risk that are relevant to RIRP after spinal SABR.