Histopathological Outcomes after Irreversible Electroporation for Prostate Cancer: Results of an Ablate and Resect Study

Abstract

Purpose: Irreversible electroporation is a tissue ablation modality that uses high voltage electric energy to induce an increase in cell membrane permeability. This causes destabilization of the existing cellular transmembrane potential leading to cell death, due to the inability to maintain cellular homeostasis. This phase I-II study was designed to evaluate the histopathological outcomes of irreversible electroporation to prostate and surrounding tissue in radical prostatectomy specimens.

Materials and methods: Sixteen patients with prostate cancer underwent an irreversible electroporation ablation without curative intent, followed by radical prostatectomy scheduled 4 weeks later. For histopathological examination of the prostate, whole mounted tissue slices were examined by dedicated genitourinary pathologists. The borders of the ablation zone and residual tumor were outlined on the slides.

Results: The irreversible electroporation ablation zones were characterized as areas of fibrosis, necrosis and loss of epithelial tissue in terms of denudation in the glandular structures. The ablation zone was well demarcated, showing trenchant delineations between viable and nonviable tissue. The ablated tissue showed mild to moderate inflammation, with atrophic cells in 1 case. The area was surrounded by hemorrhage at the location of the electrodes. No skip lesions or viable tissue was seen in the ablation zone. Fibrinoid necrosis of the neurovascular bundle was observed in 13 patients and denudation of the urothelium of the prostatic urethra was seen in 9.

Conclusions: Histopathological assessment of the prostate 4 weeks after irreversible electroporation ablation showed sharply demarcated fibrotic and necrotic tissue in the ablation zone. No viable tissue was observed in the irreversible electroporation ablation zone.

Keywords: ablation techniques; electroporation; pathology; prostatic neoplasms.