2583 - Stereotactic Body Radiotherapy (SBRT) Boost Following Urgent 3D Conformal Radiotherapy in the Treatment of Metastatic Epidural Spinal Cord Compression (MESCC): A Phase I Feasibility Trial
Presenter(s)
E. Donovan1,2, K. L. Schnarr3, J. N. Greenspoon4, J. Wright5, C. Hann6, A. C. Whitton5, T. Chow5, Y. Wang7, S. Parpia1, T. J. Whelan4, and A. Swaminath8; 1McMaster University - Juravinski Cancer Centre, Hamilton, ON, Canada, 2Department of Radiation Oncology, McMaster University, Hamilton, ON, Canada, 3Division of Radiation Oncology, Juravinski Cancer Centre, Hamilton, ON, Canada, 4McMaster University, Hamilton, ON, Canada, 5Juravinski Cancer Centre, Hamilton, ON, Canada, 6Juravinski Cancer Centre-McMaster University, Hamilton, ON, Canada, 7McMaster, Hamilton, ON, Canada, 8Juravinski Cancer Centre, McMaster University, Hamilton, ON, Canada
Purpose/Objective(s): Metastatic epidural spinal cord compression (MESCC) is a devastating complication of advanced malignancy resulting in significant functional deterioration. Palliative 3D-conformal radiotherapy (3DCRT) is the standard treatment in non-surgical candidates, but pain, motor and neurologic outcomes are variable. We conducted a pilot study to determine if a stereotactic body radiotherapy (SBRT) boost in addition to 3DCRT would be feasible, and what effects this would have on toxicity and functional outcomes.
Materials/Methods: Eligible patients included those with a solid malignancy, evidence of at least Bilsky 1c MESCC, and Rades motor scale function of at least 3. Patients were initially treated with 3DCRT (either 20 Gy/5 fractions or 8 Gy/1 fraction). SBRT boost was delivered within 4-6 weeks following 3DCRT, using a robotic radiosurgery technique, to a dose of 18-24 Gy/2 fractions. The primary outcome was feasibility of planning and delivery of 3D CRT and SBRT boost, with a success rate defined as 80% of accrued patients (95% confidence interval 75-97%). Secondary endpoints included changes in motor and ambulatory function, pain control (using Brief Pain Inventory), toxicity, as well as quality of life (QoL) measured using EORTC QLQ-c30 and BM22 questionnaires. Planned sample size was 30 patients.
Results: Sixteen patients were initially accrued from 2018-2023, the trial closed to slow accrual due to COVID-19. 13 patients were treated successfully with SBRT boost following 3DCRT, meeting the primary outcome (0.81, 0.57-0.93). Median baseline motor score was 7 normal (range 2-7), pain score was 5.5 (1-10), and most patients were ambulatory. Most had a solitary spinal site of metastasis (53.3%), and Bilsky 1c or 2 MESCC (66.7%). A majority received 20 Gy/5 fraction 3DCRT (81.3%), and SBRT boost was given a median of 36 days afterwards (33-50.1 IQR). Motor function was maintained in 76.9% and improved by 2 points from baseline in 15.4% of patients at 1-month post-SBRT boost and was subsequently maintained in patients at 3 and 6 months. Ambulatory function improved in 15.4% and was maintained in 69.2% of patients at 1 month, and improved again at 3- and 6-months post SBRT in 18.2% and 12.5% respectively. Pain improved in 23.1%, 18.2% and 37.5% of patients at 1, 3 and 12 months respectively. Only 1 Grade 3 toxicity (chest wall pain) occurred which resolved at 3 months. Median global QoL improved from baseline (69.2), to 76.3, 76.6 and 82.5 at 1,3 and 6 months respectively. BM 22 scores improved in functional and pain domains at 1,3, and 6 months. There were 2 local recurrences (143 and 236 days), and median survival of the entire cohort was 8.9 months (7.8-NR)
Conclusion: SBRT boost following 3DCRT for MESCC was feasible, with no added neurological toxicity, and resulted in moderate improvements or prolonged maintenance of motor and ambulatory function, and pain control. QoL tended to improve over time from treatment. This regimen may provide additional benefit for select MESCC patients.