2589 - Salvage Stereotactic Radiation for Recurrent or Progressive Metastatic Spine Disease after Initial Stereotactic Radiation
Presenter(s)
A. N. Elguindy1,2, E. R. Cochran1, K. Fernando1, M. Addington1, K. N. Dibs1, E. Yap1, R. S. Handschuh1, J. B. Elder3, V. Chakravarthy3, D. J. Konieczkowski1, S. Beyer4, S. Zhu4, R. Singh4, R. Raval4, J. C. Grecula1, A. Chakravarti4, J. D. Palmer4, and D. M. Blakaj1; 1Department of Radiation Oncology, James Cancer Hospital/Wexner Medical Center, The Ohio State University, Columbus, OH, 2Department of Radiation Oncology, El-Demerdash Hospitals, Ain Shams university, Cairo, Egypt, 3Department of neurosurgery, The James Cancer Center, Ohio State University Wexner Medical Center, Columbus, OH, 4Department of Radiation Oncology, The Ohio State University Wexner Medical Center, Columbus, OH
Purpose/Objective(s): Spine stereotactic radiation therapy (SRT) provides better pain relief and local control for metastatic spine lesions compared to conventional radiation. However, re-irradiating recurrent cases remains a challenge. We aim to present our experience with patients who underwent salvage radiotherapy following an initial radiotherapy
Materials/Methods: A single institute retrospective study was conducted on patients who had spine re-irradiation between 2016 and 2024. Re-irradiation was defined as a new course of radiotherapy to a previously irradiated volume or where cumulative dose concerns existed, regardless of geometric overlap. Patients had follow-up MRI scans every three months. Radiation toxicity was graded per Common Terminology Criteria for Adverse Events (CTCAE) v5.0. Dose data from each treatment—targeting the spinal cord (SC), SC+2 mm (PRV), and cauda equina (CE), and CE PRV—were used to calculate equivalent dose of 2 Gy (EQD2). The dose max (dmax) was reported as volume of 0.03 cc
Results: A total of 86 patients (98 spine levels) were included in the study, with a median follow-up of 10.3 months (range: 1–98 months). The median age was 65 years (range: 25–86 years). The cohort was 60 males (68%) and 26 females (32%). Most patients had Karnofsky Performance Status (KPS) greater than 80% (89%, n=77), while 11% had a KPS below 80%. Common primary cancer included non-small cell lung cancer (24%), renal cell carcinoma (19%), thyroid cancer (13%), prostate cancer (10%), and sarcoma (8%). Regarding decompressing surgery, 41 patients (48%) had surgery before the first or the second course. The majority (75%) received SRT in the first course with median dose 27Gy in 3 fractions, and 82% received SRT in the second course with median dose 27Gy in 3 fractions. The median interval between first and second treatment courses was 10 months (IQR: 5.3–19.5 months). The 1-year OS and LC were 45% and 89%, respectively. For the entire cohort, the median cumulative EQD2 for SC dmax and PRV02 were 34 Gy (range: 13-69), and 56 Gy (range: 10-122), respectively. The median cumulative EQD2 for CE dmax and PRV were 54 Gy (range: 20-120), and 74 Gy (range: 30-146), respectively. Four patients (5%) developed radiation induced grade 3 myelopathy. The median cumulative EQD2 for SC dmax and PRV02 were 31 Gy (range: 26-36), and 72 Gy (range: 42-102), respectively. The median cumulative EQD2 for CE dmax and PRV02 were 89 Gy (range: 58-120) and 116 Gy (range: 86-146), respectively.
Conclusion: To our knowledge, this is one of the largest studies reporting outcomes of SRT followed by re-SRT using 27 Gy in 3 fractions or 30 Gy in 5 fractions for spinal metastases, with an emphasis on reporting cumulative EQD2 of radiation induced myelopathy patients. Initial constraints were utilized showing efficacy and safety. SC and CE PRVs showed clear difference in myelopathy cases compared to entire cohort. Given the complexity of these treatments, multidisciplinary management is essential, and further prospective evaluation is warranted.