Systematic Review of the Safety and Efficacy of Irreversible Electroporation

Summary

This article serves as a comprehensive review of the clinical application of irreversible electroporation (IRE) in the use of ablation of solid tumors of the liver, pancreas, kidney, and lung. A relatively novel treatment, the premise of IRE is its ability to induce cell death through non-thermal electrical disruption of the cell membrane while preserving the extracellular matrix. The putative advantage of this therapy is its ability to allow for ablations close to vital structures such as the biliary and portal venous systems without causing them damage. The authors consolidated all in-human published reports of the use of IRE in solid tumors, resulting, after exclusion, in 16 studies made up of 221 patients and 325 treated tumors. The vast majority of these treatments were those in the liver (n = 129) and pancreas (n = 69). There were a total of 43 (22%) likely IRE-related complications, of which 28 (64%) were mild/moderate complications (Grade I/II). It should be noted that of the 129 liver IRE procedures, only 6 reported damage to a portal triad structure. Due to the strong electric pulses used in IRE, the authors also reported cardiac arrhythmia rates and uncontrolled muscle contractions, finding an incidence of 4% and 0%, respectively. More benign atrial arrhythmias were observed when using a synchronized machine, and muscle paralytic was routinely administered. Efficacy data was most robust in the hepatic ablations, with a total of 106 patients and 185 tumors treated (median size 1-3 cm). Primary efficacy was reported as 67-100% over follow-up periods ranging from 3-18 months. The authors conclude that the available level of evidence for IRE is low, although it appears safe and relatively effective on smaller lesions.



Table 3. Efficacy of Hepatic IRE demonstrates overall primary efficacy ranging from 67-100% across a number of primary and metastatic liver lesions.

Commentary

This paper reviews a relatively new and unique technique to allow for a potentially curative therapy for patients who previously would not be offered such. This review is limited by the data which the reviewers had available to consolidate. The safety and efficacy profiles seem encouraging based on the available studies. However, there is a significant gap in the quality and quantity of the more traditional RF and microwave ablation data. The theory behind altered cell membrane permeability in the use of ablation has been well studied in the pre-clinical setting, and it does seem to have effectiveness in clinical practice. However, the complication rate is not trivial, and implementing IRE in practice requires careful planning from the operator to the anesthesia team. The fact that this therapy could become a primary curative treatment in some settings for central liver lesions as well as pancreatic lesions is encouraging. Future directions are promising with ten active studies investigating IRE.

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Scheffer HJ, Nielsen K, de Jong, MC, et al. Irreversible Electroporation for Nonthermal Tumor Ablation in the Clinical Setting: A Systematic Review of Safety and Efficacy. J Vasc Interv Radiol. 2014; 25: 997-1011.

Post Author:
Daniel P. Sheeran, MD
Assistant Professor
Department of Radiology and Medical Imaging
Section of Vascular and Interventional Radiology
University of Virginia