Stereotactic Body Radiotherapy Boost After Palliative Radiotherapy for Spinal Cord Compression

Stereotactic Body Radiotherapy (SBRT) Boost Following Urgent 3D Conformal Radiotherapy in the Treatment of Metastatic Epidural Spinal Cord Compression (SCC): A Phase I Feasibility Trial

Spinal cord compression (SCC) is a devastating complication of advanced malignancy, and can cause significant deterioration in function and quality of life (QoL). The goal of treatment is to improve functional status and symptoms, but the optimal treatment regimen for these patients has not been thoroughly established. Many patients with SCC present with uncontrolled systemic disease and poor performance status, and are not eligible for standard surgical resection. They are generally treated with 3D conformal palliative RT (3DCRT) alone, however recent trials suggest that less than 70% of patients are ambulatory, that the re-establishment of ambulation in non-ambulatory patients is poor, and the duration of improvement is guarded with radiotherapy alone.

Recently, stereotactic body radiotherapy (SBRT) used alone or after previous radiotherapy to treat spinal metastasis has demonstrated superior results in pain control, tumour response and durability. SBRT requires time for careful planning, and many patients with neurologic symptoms must be treated immediately to prevent progression. Therefore the role of SBRT is still unclear in this patient population, although it seems to be a potential alternative to surgical decompression in patient not suitable for surgery. The investigators propose a feasibility study to investigate the potential benefits of dose escalation with a sequential SBRT boost to urgent 3D CRT in the setting of SCC. This regimen will allow inoperable patients to receive urgent 3DCRT while simultaneously creating the opportunity for superior outcomes with SBRT. The investigators also aim to characterize the effect on motor function and ambulation, pain and QoL. This study could stimulate further multi-center randomized trials in this area, improve motor function and patient-reported QoL, and contribute to improving oncology care in Canada in a meaningful way.

Inclusion Criteria:

1. Diagnosis of metastatic malignancy (radiologic or pathologic)
2. Evidence of disease in vertebral body with epidural component such that Bilsky radiologic score is 1c-2 on MRI (abuts spinal cord without cord compression (1c), or spinal cord compression but with visible CSF (2)
3. Motor function (MF) of 3 or greater

Exclusion Criteria:

1. Surgical candidate
2. Instability of vertebral bodies with or without bony retropulsion requiring surgical intervention or hardware placement
3. Previous radiotherapy course to same region of spine with overlapping fields (prior to phase I course) at discretion of treating radiation oncologist
4. No CT or MRI within previous 3 months
5. Life expectancy estimated <3 months
6. Performance status KPS<40
7. On active chemotherapy or targeted therapy or immunotherapy (must be stopped for at least one week prior to and following)
8. Pregnant or lactating
9. Contraindications to radiotherapy (eg. active autoimmune disease requiring medication)
10. Inability to lie flat comfortably for at least 20 minutes
11. Age < 18