Irreversible electroporation (IRE) in renal cell carcinoma (RCC): a mid-term clinical experience

To evaluate the safety and efficacy of CT-guided IRE of clinical T1a (cT1a) renal tumours close to vital structures and to assess factors that may influence the technical success and early oncological durability.

CT-guided IRE (2015-2020) was prospectively evaluated. Patients' demographics, technical details/success, Clavien-Dindo (CD) classification of complications (I-V) and oncological outcome were collated. Statistical analysis was performed to determine variables associated with complications. The overall 2- and 3-year cancer-specific (CS), local recurrence-free (LRF) and metastasis-free (MF) survival rates are presented using the Kaplan-Meier curves.

Thirty cT1a RCCs (biopsy-proven/known VHL disease) in 26 patients (age 32-81 years) were treated with IRE. The mean tumour size was 2.5 cm and the median follow-up was 37 months. The primary technical success rate was 73.3%, where 22 RCCs were completely IRE ablated. Seven residual diseases were successfully ablated with cryoablation, achieving an overall technical success rate of 97%. One patient did not have repeat treatment as he died from unexpected stroke at 4-month post-IRE. One patient had CD-III complication with a proximal ureteric injury. Five patients developed > 25% reduction of eGFR immediately post-IRE. All patients have preservation of renal function without the requirement for renal dialysis. The overall 2- and 3-year CS, LRF and MF survival rates are 89%, 96%, 91% and 87%.

CT-guided IRE in cT1a RCC is safe with acceptable complications. The primary technical success rate was suboptimal due to the early operator's learning curve, and long-term follow-up is required to validate the IRE oncological durability.

• Irreversible electroporation should only be considered when surgery or image-guided thermal ablation is not an option for small renal cancer. • This non-thermal technique is safe in the treatment of small renal cancer and the primary technical success rate was 73.3%. • This can be used when renal cancer is close to important structure.