NCOG-03. FACTORS ASSOCIATED WITH ADJACENT LEVEL TUMOR PROGRESSION IN PATIENTS RECEIVING SEPARATION SURGERY FOLLOWED BY SPINE STEREOTACTIC RADIOSURGERY FOR METASTATIC EPIDURAL SPINAL CORD COMPRESSION

Abstract

Abstract INTRODUCTION Separation surgery followed by spine stereotactic radiosurgery (SSRS) has been shown to achieve favorable rates of local tumor control and patient-reported outcomes in patients with metastatic epidural spinal cord compression (MESCC). If left untreated, MESCC causes severe pain, progressive neurological impairment, and eventual paraplegia with a median survival of 3-6 months. The present study aimed to identify factors associated with adjacent level progression and examine its impact on overall survival (OS) in this population. METHODS This study included 39 patients who received separation surgery followed by SSRS for MESCC. Preoperative, postoperative, and post-SSRS MRIs were used to measure amount of epidural disease, amount of local bone marrow involvement, and adjacent level epidural (AEP) and osseous (AOP) progression. Factors associated with AEP and AOP were examined using the log-rank test and cox proportional hazards modeling. RESULTS Median OS in our cohort was 14.7 mo (2.07-96.3). AEP and AOP were observed in 4/39 (10.3%) and 16/39 (41.0%) patients at a mean of 6.1±5.4 mo and 5.3±5.3 mo post-SSRS, respectively. AEP (7.52 vs. 17.1 mo, p = 0.014) and AOP (13.0 vs. 17.1 mo, p = 0.047) were each significantly associated with decreased OS. Factors associated with AEP included primary tumor histology, low-dose hypofractionated SSRS, increased time from surgery to SSRS, and greater amount of local epidural disease preoperatively (p < 0.05). Factors associated with AOP included greater amount of local bone marrow infiltration by tumor pre- and postoperatively and greater amount of local epidural disease postoperatively (p < 0.05). Primary tumor histology and increased time from surgery to SSRS were associated with AOP by trend (p < 0.10). CONCLUSION This study identifies factors associated with adjacent level progression and shows that AEP and AOP are associated with shorter OS in patients receiving separation surgery followed by SSRS for MESCC.