ESTRO 2023

Session Item

Sunday

May 14

10:30 - 11:30

Hall A

Haematology - CNS

Chair: , Italy;

Chair: , Denmark

Session Type: Proffered Papers

Track: Clinical

Journey:

11:00 - 11:10

Long-term results from a phase 1 trial of spine SBRT in inoperable patients with cord compression

Amol Ghia, USA

Presentation Number: OC-0440

Abstract

Abstract Title:

Long-term results from a phase 1 trial of spine SBRT in inoperable patients with cord compression

Authors:

Amol Ghia¹, Nandita Guha-Thakurta², Jing Li¹, Stephen Settle³, MaryFrances McAleer¹, Tina Briere⁴, Claudio Tatsui⁵, Paul Brown⁶, Thomas Beckham¹, Chenyang Wang¹, Debra Yeboa¹, Eric Chang⁷, Laurence Rhines⁵

¹University of Texas, MD Anderson Cancer Center, Radiation Oncology, Houston, USA; ²University of Texas, MD Anderson Cancer Center, Diagnostic Radiology, Houston, USA; ³Alaska Cyberknife Center, Radiation Oncology, Anchorage, USA; ⁴University of Texas, MD Anderson Cancer Center, Radiation Physics, Houston, USA; ⁵University of Texas, MD Anderson Cancer Center, Neurosurgery, Houston, USA; ⁶Mayo Clinic, Radiation Oncology, Rochester, USA; ⁷University of Southern California, Keck School of Medicine, Radiation Oncology, Los Angeles, USA

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Purpose or 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 related toxicity and radiographic local control (LC).

Material and Methods

Patients with MESCC in the thoracic spine deemed inoperable with no prior history of radiation at the site of interest were enrolled on this prospective Phase 1 single institution protocol (Figure 1). Single fraction SSRS was delivered to a histology dependent prescription dose of 18 or 24 Gy. Spinal cord constraint relaxation was performed from an initial allowable Dmax cohort of 10 Gy only if tumor progression occurred. If the risk of radiation induced spinal cord myelopathy (RM) remained lower than the risk of tumor progression, then the cord Dmax was elevated in 2 Gy increments to a maximum of 16 Gy in the final cohort. Patients were monitored every 3 months with follow-up visits, MRI scans and validated patient reported outcome surveys.

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. The most common histology was renal cell carcinoma (n=12). The most common GTV prescription dose was 18 Gy (n=17) followed by 24 Gy (n=15). The median age was 62.7 yrs (range 35-81 yrs). 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 32 patients treated with SSRS, 4 were lost to follow-up without post-SSRS evaluation. Of the remaining 28 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%, respectively, while the median LC was not met 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)(Figure 2). 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.