When you were growing up, your mom or dad no doubt cautioned you against poking anything into an electrical outlet. You didn’t need to understand the concept of conductance; you simply had to grasp that a painful thing called a shock would be the result. Depending on how dramatic the message was, you might have even been worried that you could die!
In fact, the cells in your body excel at conducting electricity, which plays a key role in everything you think and do. The University of Maryland explains it nicely:
Electricity is required for the nervous system to send signals throughout the body and to the brain, making it possible for us to move, think and feel. So, how do cells control electrical currents? The elements in our bodies, like sodium, potassium, calcium, and magnesium, have a specific electrical charge.
Humans have known about electricity since ancient times, but did not know how to harness it. In Benjamin Franklin’s famous 1752 kite experiment, he used conductivity to transfer electrical energy from lightning into a recently developed device called a Leyden jar that temporarily stores electricity.
Now there’s a new experimental method that is being studied for the focal treatment of prostate cancer (PCa). It’s called Irreversible Electroporation (IRE). It does not use extreme temperatures like cryotherapy (freezing) or laser ablation (heat). Instead, it takes advantage of the body’s conductance properties to selectively destroy cancer cells. When they are exposed to brief, controlled electrical fields, tiny pores open up in the membrane that contains the cell’s internal environment and DNA. At high voltage, the pores can’t close so the cell becomes irreversibly permeable. Since the cell can no longer protect its contents, it dies off naturally. The body then does a clean-up job with the resulting waste matter.
Nearby healthy structures (nerve bundles, urinary sphincter muscles, collagen architecture) are preserved since the cancer cells are more susceptible than healthy cells. In addition, imaging allows careful treatment planning in order to target the tumor. The procedure is performed under general anesthesia and a mild paralytic drug to prevent involuntary movements during the electrical charge. IRE is now in international clinical trials that are showing promising results.
For example, a study out of Shanghai, China reports a clinical trial with 117 patients whose IRE was administered using a device called a Composite Steep Pulse Therapeutic Apparatus.[i] Patient enrollment criteria included PSA <20 ng/mL, clinical state T2c or less, and Gleason score ≤7. All patients had a pretreatment multiparametric MRI to determine the PI-RADS score and to map the lesion for treatment. They also underwent a pretreatment transperineal biopsy for diagnosis.
The study design included a post-treatment biopsy at 6 months to determine the presence of any clinically significant PCa (csPCa), defined as any biopsy core with Gleason score ≥ 7, or Gleason score of 6 plus maximum cancer core length > 3 mm (or an increase from the original cancer burden). The authors would compare their 6-month csPCA rate vs. an acceptable rate of 20% need for retreatment after focal therapy using thermal methods (heat or freezing), as derived by an expert consensus panel.[ii]
The findings of the Chinese team were calculated based on 100 patients who had a 6-month post treatment biopsy. Of those, 6 patients (6%) were found to have csPCa (1 in the treatment zone and 5 outside the treatment zone.) Their total rate of 6% was favorable compared with the historical consensus rate of 20% retreatment, but what is most compelling is the very low rate of in-field recurrent csPCa; only 1 patient out of 100 had recurrence in the treatment zone at 6 months. This speaks well of IRE’s potential ability to destroy cancer cells. The authors conclude, “The rate of 6-month csPCa with H FIRE ablation was lower than the historical control using other energy platforms.” However, in this patient cohort there was a rather high complication rate of 37.6% during the six-month follow-up period; while most of the complications were urinary events, 9% of patients experienced some degree of erectile dysfunction. The urinary complications during the follow-up were more prevalent than with other thermal ablation modalities.
The Chinese study certainly offers reason for optimism, particularly in cancer control for low-risk patients, but long term studies are needed to determine how durable the results are. IRE is also being studied for the treatment of other tumor cancers (e.g., pancreatic cancer), with tumor size being a limitation since larger lesions are not amenable to IRE. In addition, reversible electroporation at lower voltage is in clinical trials as a method of delivering chemotherapy directly into cancer cells, then closing the pores so individual cancer cells die from the chemicals within the cell.
IRE appears to be a promising technology for focal treatment of prostate tumors, and all of us at the Sperling Prostate Center will be following research results as they are published. More importantly, the Sperling Prostate Center already offers the three most advanced MRI-guided focal treatment methods: Focal Laser Ablation (FLA), TULSA-PRO, and Exablate MR-guided Focused Ultrasound. Contact us for more information.
NOTE: This content is solely for purposes of information and does not substitute for diagnostic or medical advice. Talk to your doctor if you are experiencing pelvic pain, or have any other health concerns or questions of a personal medical nature.
[i] Wang H, Xue W, Yan W, et al. Extended Focal Ablation of Localized Prostate Cancer With High-Frequency Irreversible Electroporation: A Nonrandomized Controlled Trial. JAMA Surg. Published online July 06, 2022.
[ii] Donaldson IA, Alonzi R, Barratt D, Barret E et al. Focal therapy: patients, interventions, and outcomes–a report from a consensus meeting. Eur Urol. 2015 Apr;67(4):771-7.