Premature Termination of a Randomized Controlled Trial on Image-Guided Stereotactic Body Radiotherapy of Metastatic Spinal Cord Compression.

Lessons Learned: It is possible to plan and treat some patients with stereotactic body radiotherapy (SBRT) in a timely fashion in an acute setting. Advanced and, in some indications, already implemented technologies such as SBRT are difficult to test in a randomized trial.

Background: Stereotactic body radiotherapy (SBRT) in metastatic spinal cord compression (MSCC) could be an alternative to decompressive surgery followed by fractionated radiotherapy.

Methods: In a randomized, single-institution, noninferiority trial, patients with MSCC were assigned to stereotactic body radiotherapy of 16 Gy in 1 fraction or decompression surgery followed by fractionated radiotherapy of 30 Gy in 10 fractions. Primary endpoint was ability to walk by EQ5D-5L questionnaire. Based on power calculations, 130 patients had to be included to be 89% sure that a 15% difference between the treatment arm and the experimental arm could be detected.

Results: Ten patients were accrued in 23 months, with six patients allocated to surgery and four patients to stereotactic body radiotherapy. The trial was closed prematurely because of poor accrual. One patient undergoing surgery and one patient undergoing stereotactic body radiotherapy were unable to walk at 6 weeks. Two patients were not evaluable at 6 weeks.

Conclusion: A randomized, phase II, clinical trial comparing surgery followed by fractionated radiotherapy or image-guided SBRT of MSCC was initiated. SBRT was shown to be feasible, with three out of four patients retaining walking function. The trial was determined futile as a result of low accrual.