RESUMO
BACKGROUND: Patients with previously irradiated metastatic epidural spinal cord compression (MESCC) who are not surgical candidates are at high risk of neurologic deterioration due to disease in the setting of limited treatment options. We seek to establish the feasibility of using salvage spine stereotactic radiosurgery (SSRS) allowing for spinal cord dose constraint relaxation as the primary management of MESCC in inoperable patients monitoring for radiation related toxicity and radiographic local control (LC). METHODS: Inoperable patients with previously irradiated MESCC were enrolled on this prospective Phase 1 single institution protocol. Single fraction SSRS was delivered to a prescription dose of 18 Gy. Spinal cord constraint relaxation was performed incrementally from an initial allowable Dmax cohort of 8 Gy to 14 Gy in the final planned cohort. Patients were monitored every 3 months with follow-up visits and MRI scans. RESULTS: The trial was closed early due to slow accrual. From 2011 to 2014, 11 patients were enrolled of which 9 patients received SSRS. Five patients were in the 8 Gy cord Dmax cohort and 4 in the 10 Gy cord Dmax cohort.The median overall survival (OS) was 11.9 months (95% CI 7.1, 22 months). Of the 9 patients treated with SSRS, 1 died prior to post-SSRS evaluation. Of the remaining 8 patients, 5 experienced a local failure. Three of the five were treated with surgery while two received systemic therapy. Two of the five failures ultimately resulted in loss of neurologic function. The median LC was 9.1 months (95%CI 4.8, 20.1 months). With a median clinical follow-up of 6.8 months, there were no cases of RM. CONCLUSIONS: Despite the limited life expectancy in this high-risk cohort of patients, strategies to optimize LC are necessary to prevent neurologic deterioration. Larger prospective trials exploring optimal dose/fractionation and cord constraints are required.
RESUMO
PURPOSE: 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. METHODS AND MATERIALS: Inoperable patients with thoracic MESCC and no history of radiation were enrolled on this prospective phase 1 single-institution protocol. SSRS was delivered to a histology-dependent prescription dose of 18 or 24 Gy. Incremental spinal cord constraint relaxation was performed from a Dmax cohort of 10 Gy up to 16 Gy only if tumor progression occurred and the risk of radiation-induced myelopathy (RM) remained lower than the risk of tumor progression. RESULTS: Thirty-two patients enrolled on the trial; 4, 12, 9, and 7 patients were in the 10 Gy, 12 Gy, 14 Gy, and 16 Gy cord Dmax cohorts, respectively. At baseline, there were 2 sites with MESCC grade 1A, 10 sites with grade 1B, 10 sites with grade 1C, 9 sites with grade 2, and 1 site with grade 3 disease. Among the 28 evaluable patients, the median overall survival was 28.6 months (95% confidence interval [CI], 9.2-48.0 months), and the 1-year local control was 89% (95% CI, 74%- 97%). With a median follow-up of 17 months, there were no cases of RM (upper 95% CI, 12%). In the cohort receiving a cord Dmax of 16 Gy, there were no cases of RM (upper 95% CI, 39%) with a median follow-up of 17 months (range, 12.7-21.0 months). CONCLUSIONS: SSRS is a safe and effective tool in patients with MESCC. In high-risk inoperable patients with MESCC receiving SSRS, dose constraint relaxation of the cord constraint dmax to 16 Gy may be considered to optimize local control, with the acknowledgment that this is based on 6 evaluable patients who received this dose in this trial.