Safety and Effectiveness of Irreversible Electroporation in Lymph Node Metastases

Abstract

Purpose: Demonstrating the safety and efficacy of percutaneous irreversible electroporation (IRE) for the treatment of lymph node metastases.

Materials and methods: An IRB-approved, single-center retrospective review was performed on patients with lymph node metastases gastrointestinal, and genitourinary primary cancers. Primary objective safety was evaluated by assessing complications graded according to the Clavien-Dindo Classification, and efficacy was determined by tumor response on follow-up imaging and local progression-free survival (LPFS). Secondary outcome measures were technical success (complete ablation with an adequate ablative margin > 5 mm), length of hospital stay and distant progression-free survival (DPFS).

Results: Nineteen patients underwent percutaneous IRE between June 2018 and February 2023 for lymph node metastases, close to critical structures, such as vasculature, bowel, or nerves. The technical success was achieved in all cases. Complications occurred in four patients (21.1%), including two self-limiting grade 1 hematomas, a grade 1 abdominal pain, and grade 2 nerve pain treated with medication. Seventeen patients were hospitalized overnight, one patient stayed two nights and another patient stayed fourteen nights. Median follow-up was 25.5 months. Median time to local progression was 24.1 months (95% CI: 0-52.8) with 1-, 2-, and 5-year LPFS of 57.9%, 57.9% and 20.7%, respectively. Median time to distant progression was 4.3 months (95% CI: 0.3-8.3) with 1-, 2-, and 5-year DPFS of 31.6%, 13.2% and 13.2%, respectively.

Conclusion: IRE is a safe and effective minimally-invasive treatment for lymph node metastases in locations, where temperature dependent ablation may be contraindicated. Care should be taken when employing IRE near nerves.

Keywords: Irreversible electroporation (IRE); Lymph node metastases; Tumor response.

Fig. 1

Kaplan–Meier survival curves of (A) local progression-free survival (LPFS) and (B) distant progression-free survival after irreversible electroporation (IRE) per patient

Fig. 2

A 66-year-old female admitted with rectal pain. Past medical history of adenocarcinoma of the rectum diagnosed in 2019, underwent loop sigmoid colostomy, completed radiation and is receiving adjuvant chemotherapy (FOLFOX) upon treatment. (A) Abdominopelvic CT shows a left inguinal lymph node measuring up to 2.7 cm concerning for metastasis. Ultrasound-guided biopsy of the left inguinal lymph node with frozen samples was positive for adenocarcinoma. (B) Intraprocedural CT demonstrating intermittent placement of three 17-gauge NanoKnife IRE ablation needles. (C) Follow-up PET-CT the following day showing lack of FDG-uptake of the treated lymph node. (D) Follow-up PET-CT after 29 months showing FDG-uptake of the treated lymph node