The correlation between the electrode configuratio

Authors: W van den Bos D M de Bruin R R Jurhill C D SavciHeijink B G Muller I M Varkarakis A Skolarikos P J Zondervan M P LagunaPes H Wijkstra T M de Reijke J J M C H de la Rosette

Publish Date: 2015/08/22

Volume: 34, Issue: 5, Pages: 657-664

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Abstract

Irreversible electroporation IRE is a novel minimally invasive therapy for prostate cancer using short electric pulses to ablate prostate tissue The purpose of this study is to determine the IRE effects in prostate tissue and correlate electrode configuration with the histology of radical prostatectomy RP specimens We hypothesize that the area within the electrode configuration is completely ablated and that the area within the electrode configuration is predictive for the ablated area after treatmentA prospective phase I/II study was conducted in 16 consecutive patients with histopathologically confirmed prostate cancer scheduled for RP Focal or extended IRE treatment of the prostate was performed 4 weeks prior to RP The locations of the electrodes were used to calculate the planned ablation zone Following RP the specimens were processed into wholemount sections histopathology PA was assessed and ablation zones were delineated The area of the tissue alteration was determined by measuring the surface The planned and the histological ablation zones were compared analysed per individual patient and per protocol focal vs extendedAll cells within the electrode configuration were completely ablated and consisted only of necrotic and fibrotic tissue without leaving any viable cells The histological ablation zone was always larger than the electrodes configuration 29 times larger for the 3 electrodes configuration and 25 times larger for the ≥4 electrode configuration These ablation effects extended beyond the prostatic capsule in the neurovascular bundle in 13 out of 15 casesProstate cancer has become the most prevalent cancer in men and forms a significant health risk in the Western world 1 PSA tests are currently performed regularly and imaging techniques have improved leading to a considerably increased detection of localized prostate cancer 1 The current treatment options for localized prostate cancer are active surveillance and therapy with curative intent surgery or radiotherapy depending on the stage of the tumour and patients’ consideration A variety of ablative therapies has been introduced for treatment of localized prostate cancer It functions as middle ground between the traditional options The rationale behind these socalled focal therapies is to target only the tumourous areas and leave healthy tissue and adjacent structures intact Most used ablative technologies are cryotherapy highintensity focused ultrasound HIFU and radiotherapy 2 A novel technique in the armamentarium is irreversible electroporation IRE It uses pulsed highvoltage lowenergy direct electric current for ablation The electric energy is delivered through needleelectrodes placed circumferential around the tumour zone Cellmembrane potentials are disturbed by the consecutive highvoltage usually around 1500 V/cm electric pulse trains between at least two spatially separated electrodes which leads to irreversible permeability of cell membranes and results in apoptotic cell death 3 Literature on IRE reports advantages as sparing surrounding vital structures including blood vessels and connective tissue 4 By sparing these structures unharmed patients might maintain their potency and continence Successfully treating prostate cancer requires an accurate prediction of the treatment zone through treatment planning Planning of IRE is currently based on mathematical and numerical models in multicellular tissue models and animals studies 5 6 7 The aim of this study was to assess the IRE ablation zone in specimens from radical prostatectomies by using different ablation protocols and to correlate the crosssectional ablation zone on histopathology with the electrode configuration We hypothesize that 1 the area within the electrode configuration is completely ablated 2 the area within the electrode configuration is predictive for the crosssectional ablated area after treatment irrespective to the used ablation protocol

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