Irreversible electroporation of unresectable soft tissue tumors with vascular invasion: effective palliation

Irreversible electroporation (IRE) has recently been added as an additional therapeutic ablative option in patients with locally advanced cancers (LAC) involving vital structures. IRE delivers localized electric current by peri-tumoral discrete probes to attain irreversible changes in cell membrane leading to cell death. The aim of this study was to evaluate the long-term effects of IRE in the treatment of locally advanced tumors.

A prospective IRB approved evaluation of 107 consecutive patients from 7 institutions with tumors that had vascular invasion treated with IRE from 5/2010 to 1/2012. LAC was defined as primary tumor with <5 mm from major vascular structure based on pre-operative dynamic imaging or intra-operative criteria.

IRE as utilized in LAC in the liver (N = 42, 40%) and pancreas (N = 37, 35%), with a median number of lesions being 2 with a mean target size of 3 cm. IRE attributable morbidity rate was 13.3% (total 29.3%) with high-grade complications seen in 4.19% (total 12.6%). No significant vascular complications were seen, and of the high-grade complications, bleeding (2), biliary complications (3) and DVT/PE (3) were the most common. Complications were more likely with pancreatic lesions (p = 0.0001) and open surgery (p = 0.001). Calculated local recurrence free survival (LRFS) was 12.7 months with a median follow up of 26 months censured at last follow up. The tumor target size was inversely associated with recurrence free survival (b = 0.81, 95% CI: 1.6 to 4.7, p value = 0.02) but this did not have a significant overall survival impact.

IRE represents a novel therapeutic option in patients with LAC involving vital structures that are not amenable to surgical resection. Acceptable to high local disease control and the long LRFS can be achieved with this therapy in combination with other multi-disciplinary therapies.