Feasibility and Safety of Irreversible Electroporation in Locally Advanced Pelvic and Retroperitoneal Tumors

Retroperitoneal and pelvic tumors include a variety of neoplasms from colorectal, bladder, ovarian, and testicular cancers to sarcomas. Appropriate treatment strategies for locally advanced retroperitoneal tumors have historically included radiation therapy, chemotherapy, ablation, and surgical resection. Of these, an R0 surgical resection at the time of initial diagnosis has been shown to have the most curative potential and largest survival benefit.1 The constraints of the retroperitoneum and pelvis formed by the bony boundaries of the pelvic girdle along with the urologic, reproductive, and gastrointestinal organs within the space make surgical resection technically challenging. This difficulty is further compounded by the large size of retroperitoneal tumors that often invade adjacent organs. As such, despite aggressive surgical approach to treatment of retroperitoneal tumors often including resection of adjacent organs, a preponderance of cases are unable to obtain clear microscopic margins limiting them to an R1 or even R2 resection. Supplemental treatment modalities including chemotherapy, ablation, and radiation therapy have been used in addition to surgical resection to provide more definitive local control of retroperitoneal neoplasms that are not amenable to an R0 resection. The lack of evidence in the published literature for the efficacy of perioperative radiation therapy and systemic chemotherapy; however, has prompted the search for other modalities to supplement surgical resection to improve local tumor control. Irreversible electroporation (IRE) is a novel treatment modality that has potential to improve local control via margin enhancement of retroperitoneal and pelvic tumors. Unlike other forms of ablation, IRE does not rely on thermal energy to cause cellular death. Rather, IRE use the electrical potential of the cell membrane and a series of electrical pulses to cause the irreversible formation of micropores within the cellular membrane leading to apoptosis. IRE has been studied extensively in the treatment of hepatic and pancreatic neoplasms. Little empirical data exist, however, concerning its use in soft-tissue tumors of the retroperitoneum and pelvis. This case series presents our single-institution experience in using this new treatment modality in the management of retroperitoneal and pelvic tumors. The study consisted of a retrospective review of 15 cases in which IRE was used to supplement primary surgical resection of locally advanced pelvic and retroperitoneal tumors. A single surgical oncologist at a major tertiary care referral center in the United States treated all patients included in the series between November 2013 and April 2015. Wide resection of primary tumors with a minimum negative margin of 1.0 cm was performed where possible. IRE was then used following manufacturer’s recommended guidelines to provide margin enhancement, residual tumor ablation, or complete tumor ablation where negative margins were unable to be obtained due to pelvic constraints and involvement of adjacent organs. Patients were then followed in the immediate and intermediate postoperative period and evaluated for any complications. Tumor location, type, and size were recorded for each patient. The goal of IRE treatment along with its efficacy, number of IRE probes used, intra-and postoperative complications were recorded and analyzed for each patient. A Clavien–Dindo classification score was assigned for each complication recorded based on established guidelines.2 Results are shown in Table 1. Eight males and seven females were included in the study with a mean age of Presented as a poster at the Southeastern Surgical Congress 2016 Annual Scientific Meeting, February 22, 2016, Atlanta, GA. Address correspondence and reprint requests to Brian P. Bateson, Department of Surgery, Medical College of Georgia, Augusta University, 1120 15th Street, BI-4070, Augusta, GA 30912. E-mail: bbateson@augusta.edu.