Percutaneous irreversible electroporation for breast tissue and breast cancer: Safety, feasibility, skin effects and radiologic-pathologic correlation in an animal study

Abstract

Background: To study the safety, feasibility and skin effects of irreversible electroporation (IRE) for breast tissue and breast cancer in animal models. Methods: Eight pigs were used in this study. IRE was performed on the left breasts of the pigs with different skin-electrode distances, and the right breasts were used as controls. The electrodes were placed 1-8mm away from the skin, with an electrode spacing of 1.5-2cm. Imaging and pathological examinations were performed at specific time points for follow-up evaluation. Vital signs, skin damage, breast tissue changes and ablation efficacy were also closely observed. Eight rabbit models with or without VX2 breast tumor implantations were used to further assess the damage caused by and the repair of thin skin after IRE treatment for breast cancer. Contrast-enhanced ultrasound and elastosonography were used to investigate ablation efficacy and safety. Results: During IRE, the color of the pig breast skin reversibly changed. When the skin-electrode distance was 3mm, the breast skin clearly changed, becoming white in the center and purple in the surrounding region during IRE. One small purulent skin lesion was detected several days after IRE. When the skin-electrode distance was 5-8mm, the breast skin became red during IRE. However, the skin architecture was normal when evaluated using gross pathology and hematoxylin-eosin staining. When the skin-electrode distance was 1mm, skin atrophy and yellow glabrescence occurred in the rabbit breasts after IRE. When the skin-electrode distance was≥5mm, there was no skin damage in the rabbit model regardless of breast cancer implantation. After IRE, complete ablation of the targeted breast tissue or cancer was confirmed, and apoptosis was detected in the target tissue and outermost epidermal layer. In the ablated breasts of the surviving animals, complete mammary regeneration with normal skin and hair was observed. Furthermore, no massive fibrosis or mass formation were detected on ultrasound or through hematoxylin-eosin staining. Conclusions: After IRE, the skin architecture was well preserved when the skin-electrode distance was≥5mm. Moreover, breast regeneration occurred without mass formation or obvious fibrosis.