A Preliminary Study of a Prototype Cryoablation Needle on Porcine Livers for Pancreatic Cancer Treatment.

Despite its relatively low incidence rate compared to others, pancreatic cancer has a poor prognosis owing to its late detection and poor response to systemic chemotherapy. Because the effectiveness of chemotherapy is still restricted, the need for locoregional treatment is increasing. Cryoablation is an effective and minimally invasive treatment for some cancers, but its efficiency in pancreatic cancer is limited. Despite recent reports about promising outcomes, the optimal method and conditions of treatment are not known. In this preliminary study, we aimed to develop a cryoablation needle which can control the ablated area considering application through endoscopic ultrasonography. Here, we used a novel cryoneedle cooling system which can adjust the ablation range based on a liquid carbon dioxide refrigerant. Applied to the livers of swine, the cryoablation needle rapidly reached -60 °C within 30 s and cryoablation was performed for approximately 240 s. Based on the distance and depth, we collected real-time temperature data during the procedure. To compare the extent of cell death over time, tissue samples were collected hourly from 3 to 6 h after the procedure. Approximately 4-5 mm of tissue was ablated via cryoablation, and cell death progressed over time after cryoablation. Moreover, the ablated lesions could be regulated using an insulating agent on the needle. This preliminary study on a novel surgical cooling needle system compatible with endoscopic ultrasound for cryoablation-based pancreatic cancer treatment confirmed the efficacy of cryoablation and identified the conditions necessary to induce necrosis. Additionally, this study evaluated the effectiveness of the insulation component of the system in protecting normal cells and assessed the extent of necrosis over time after the procedure.