The Optimal Time between Embolization and Surgery for Hypervascular Spinal Metastatic Tumors : A Systematic Review and Meta-Analysis

Abstract

Objective: Preoperative transarterial embolization (TAE) of tumor feeders in hypervascular spine metastasis is known to reduce intraoperative estimated blood loss (EBL) during surgery. The effect of TAE varies for several reasons, and one controllable factor is the timing between embolization and surgery. However, the adequate timing remains unclear. This study aimed to evaluate the timing and other factors that reduce EBL in spinal metastasis surgery through a meta-analysis.

Methods: A comprehensive database search was performed to identify direct comparative studies of EBL stratified by the timing of surgery after TAE for spinal metastasis. EBL was analyzed according to the timing of surgery and other factors. Subgroup analyses were also performed. The difference in EBL was calculated as the mean difference (MD) and 95% confidence interval (CI).

Results: Among seven studies, 196 and 194 patients underwent early and late surgery after TAE, respectively. The early surgery was defined as within 1-2 days after TAE, while the late surgery group received surgery later. Overall, the MD in EBL was not different according to the timing of surgery (MD, 86.3 mL; 95% CI, -95.5 to 268.1 mL; p=0.35). A subgroup analysis of the complete embolization group demonstrated that patients who underwent early surgery within 24 hours after TAE had significantly less bleeding (MD, 233.3 mL; 95% CI, 76.0 to 390.5 mL; p=0.004). In cases of partial embolization, EBL was not significantly different regardless of the time interval.

Conclusion: Complete embolization followed by early spinal surgery within 24 hours may reduce intraoperative bleeding for the patients with hypervascular spinal metastasis.

Keywords: Bleeding; Meta-analysis; Metastasis; Therapeutic embolization; Time interval.

Fig. 1.

Flow diagram of the identification of relevant studies. Hb : hemoglobin.

Fig. 2.

A forest plot of intraoperative blood loss by surgery timing. The standard of early surgery after embolization was within 0 day or 24 hours in five studies and within 2 days or 48 hours in two studies. The early surgery group shows a trend for less bleeding, but the difference is not statistically significant. SD : standard deviation, IV : inverse variance, CI : confidence interval.

Fig. 3.

A forest plot of intraoperative blood loss by surgery timing (≤24 hours or not) in patients with complete embolization. Individual participant data from three studies showed significantly less bleeding in the early surgery group. When adding data from a study stating that complete embolization was achieved in 93% of patients, the early surgery group also shows significantly less bleeding than the late surgery group. SD : standard deviation, IV : inverse variance, CI : confidence interval.

Fig. 4.

A forest plot of intraoperative blood loss by the degree of embolization stratified by surgery timing. The complete embolization group showed less bleeding than the partial embolization group. The combination of both complete embolization and early surgery was significantly associated with reduced blood loss. SD : standard deviation, IV : inverse variance, CI : confidence interval.