Ctni-01. long-term results from a phase 1 trial of spine sbrt in inoperable patients with cord compression

PURPOSE/OBJECTIVE We seek to establish the feasibility of using spine stereotactic radiosurgery (SSRS) allowing for spinal cord dose constraint relaxation as the primary management of metastatic epidural spinal cord compression (MESCC) in inoperable patients monitoring for radiation myelopathy (RM) and radiographic local control (LC). MATERIAL/METHODS Patients with radiation naïve MESCC were enrolled on this prospective Phase 1 trial. Single fraction SSRS was delivered to a dose of 18 or 24 Gy. Spinal cord constraint relaxation was performed in sequential cohorts from an initial allowable Dmax cohort of 10 Gy up to 16 Gy only if tumor progression occurred without RM. RESULTS Thirty two patients enrolled on the trial of which 4, 12, 8 and 8 were in the 10 Gy, 12 Gy, 14 Gy and 16 Gy cord Dmax cohorts, respectively. At baseline, there were 10 sites with MESCC Grade 1B, 10 sites with Grade 1C, 9 sites with Grade 2, 2 sites with Grade 1A, and 1 site with Grade 3 disease. Of the 28 evaluable patients, the median overall survival was 32.3 months (range 5.8-122.6 mo). The 1-year and 5-year LC was 84.5% and 79.5%. The 2-year LC did not statistically differ between the 14-16 Gy cord Dmax combined cohorts and the 10-12 Gy cord Dmax combined cohorts (92.9% vs. 62.9%, p = 0.15). With a median clinical follow-up of 22.7 months (range 3-122.3 mo), there were no cases of RM including in the 13 patients who survived at least 3 years. In the cohort receiving a cord Dmax of 16 Gy, there were no cases of RM with a median follow-up of 18.6 mo (range 9.0-97.1 mo). CONCLUSION With long-term follow-up, these data demonstrate that SSRS is a safe and effective tool in patients with MESCC. Cord constraint relaxation may be considered in inoperable patients with MESCC.