Nilsson and colleagues from Uppsala University in Sweden in an interesting Phase I pilot study evaluated the irreversible electroporation procedure for the treatment of locally advanced (ostensibly unresectable) pancreatic cancer, publishing the results in the January 2014 issue of the journal, Anticancer Research.
Cells are the fundamental unit of biological life. And we know that the membrane that separates the intracellular from the extracellular world is a complicated selectively porous phospholipid bilayered structure that that functions in part as an insulator. The ion channels and other pores in the cell membrane allow electrical currents to flow between the charged fluids on the inside and outside of the cell. Thus, there is electrical potential across the cell membrane. Electroporation (sometimes called electropermeabilization) is the process whereby an externally applied electrical field can cause increased electrical conductivity and permeability of the cell membrane.
A frequent use of electroporation is to improve permeability in order to introduce an external substance into the cell (e.g., a probe, a drug, DNA). However, there is another use of electroporation (so-called irreversible electroporation) in that exceeding the maximum electroporation threshold level will cause inevitable cell death. This second use is that of the research herein discussed.
The researchers identified five patients who met their inclusion criteria. Under general anesthesia, the researchers used ultrasound to guide thin needles placed in percutaneously fashion around the pancreatic cancer tumor in each of these patients. Short bursts of direct current above the level of the electroporation threshold were administered, causing irreversible electroporation (cell death) – presumably primarily in the tumor tissue.
The authors found that one patient now became eligible for and was able to undergo a pancreaticoduodenectomy (Whipple procedure with portal vein resection). Also, two patients showed no sign of recurrence by scan or ultrasound at six months post-procedure. Finally, there were no serious untoward side-effects related to the procedure in any of the patients noted during and after the course of the treatment.
The researchers found that the treatment efficacy of percutaneous irreversible electroporation for locally advanced cancer of the pancreas appears to be promising, with a good safety profile.
This is a very positive finding that demands replication and confirmation. It would be interesting to follow the patient outcomes for a longer period – to more fully assess efficacy. The minimally invasive (percutaneous) aspect of the treatment modality adds a special interest to this approach.
Dale O’Brien, MD