2626 - Postoperative Radiotherapy for Malignant Cord Compression Treated in a Public and Private Hospital

J. Wang¹, H. R. Han², A. Vassantachart³, P. Bonney⁴, S. X. Bian², and J. C. Ye⁵; ¹Keck School of Medicine, University of Southern California, Los Angeles, CA, ²Department of Radiation Oncology, Los Angeles General Medical Center, Los Angeles, CA, ³Department of Radiation Oncology, City of Hope Medical Center, Duarte, CA, ⁴Department of Neurological Surgery, University of California San Francisco, San Francisco, CA, Los Angeles, CA, ⁵Department of Radiation Oncology, University of Southern California Keck School of Medicine, Los Angeles, CA

Purpose/Objective(s): Metastatic spinal cord compression (MSCC) is a feared complication of advanced malignancy. Timely initiation of decompressive surgery followed by radiotherapy (RT) is crucial for local control and preservation of neurologic function. We aim to retrospectively review and compare baseline characteristics and outcomes, as well as time to initiation (TTI) of postoperative RT and its association with ambulatory function of MSCC patients treated at an urban safety-net hospital (SNH) and a private academic hospital (PAH) associated within the same university system. Materials/

Methods: We included patients with Bilsky 2 or 3 MSCC who received surgery followed by RT between 2015-2022. We calculated the relative risk (RR) of worsened ambulation at 3 months relative to TTI of RT. Overall survival (OS) between the campuses was computed with the log-rank test. Cross-campus initial Rades scores were compared using Chi-square analysis.
Results: A total of 78 patients: 60 (62% male, 58% Hispanic) from the SNH and 18 (56% female, 56% White) from the PAH were identified. The most common primary malignancies were breast (18%), prostate (18%), and kidney (17%). The most common presenting symptoms at the SNH were extremity weakness (43%), pain (25%), and numbness (24%), whereas at the PAH pain (68%) was most common, followed by weakness (20%) and numbness (8%). Median TTI of RT was 36 and 37 days (p=0.46) from surgery at the SNH and PAH, respectively. Most SNH patients (98%) received adjuvant RT using 3D technique, whereas most PAH patients (77.8%) received stereotactic body radiotherapy; median BED10 was 39 and 51 Gy in the SNH and PAH, respectively. No significant difference in the initial Rades scores (p=0.13) or OS (p = 0.81) was observed between the two hospitals. 74% of patients presented with MSCC with no prior diagnosis or treatment of metastatic cancer. Of those with prior diagnosis of metastases, the median interval from diagnosis of metastasis to MSCC was 24 months, and median number of lines of systemic therapy was 2 (range 1-8). Peri-operatively, 95% (n=74) of patients were ambulatory, of whom 19% (n=15) lost ambulatory function 3 months after surgery due to recurrent spinal disease or deconditioning from disease progression. Of the 5.1% (n=4) who presented non-ambulatory, all from the SNH, 50% (n=2) regained ambulation while the other 50% did not. RR of inability to ambulate at 3 months increased with TTI of post-op RT >42 days (RR=2.4; p=0.045). Reasons for TTI >42 days included delayed RT consultation and transportation problems for patients from the SNH, and delayed healing from surgery and systemic therapy cycles prior to RT at the PAH.
Conclusion: MSCC patients in different hospital settings have varying patterns of disease presentation and face different barriers to timely initiation of postoperative RT. Delay in TTI of RT >42 days after surgery increased the RR of patients losing ambulatory function.