Effectiveness of Preoperative Embolization in Patients with Spinal Metastases: A Systematic Review and Meta-Analysis

OBJECTIVE: Debate on the effectiveness of preoperative embolization for spinal metastatic lesions, especially for nonhypervascular tumors, has persisted. The present study aimed to identify the effectiveness of preoperative embolization in patients who had undergone surgery for spinal metastasis. METHODS: Two of us (Z.T. and Z.H.) independently searched the PubMed, Embase, and Cochrane Central Register of Controlled Trials databases to identify eligible clinical studies that had compared the outcomes of patients treated surgically for spinal metastatic disease with or without preoperative embolization. The primary outcomes included intraoperative blood loss, perioperative blood loss, and transfusion requirements. The secondary outcomes include the operative time, overall survival, and complication rates. Meta-analyses were performed for subgroups of hypervascular, nonhypervascular, and mixed tumors. A fixed effects model was applied when I-2 was <50%, and a random effects model was applied when I-2 was >50%. RESULTS: A total of 12 studies (1 randomized controlled trial and 11 retrospective case-control studies), with 744 patients, were included. Significantly less intraoperative blood loss (mean difference [MD], -1171.49 mL; 95% confidence interval [CI], -2283.10 to -59.88; P = 0.039), fewer blood transfusions (MD, -3.13 U; 95% CI, -4.86 to -1.39; P < 0.001), and shorter operative times (MD, -33.91 minutes; 95% CI, -59.65 to -8.17; P = 0.010) were identified for the embolization group in the hypervascular subgroup. In the nonhypervascular and mixed tumor subgroups, no differences in effectiveness were identified in blood loss, transfusion requirement, or operative time when stratified by the use of embolization. The overall survival and complication rates were similar between the embolization and nonembolization groups in each subgroup. CONCLUSIONS: The current data support the use of preoperative embolization for hypervascular metastatic tumors to the spine. However, little evidence is available to support the use of preoperative embolization for nonhypervascular metastatic tumors to the spine.