Long-term outcomes of focal irreversible electroporation for localized prostate cancer: results of a prospective pilot study with extended follow-up

Objectives Irreversible electroporation (IRE) is a non-thermal ablative technique that may offer advantages in safety of prostate cancer (PCa) treatment. Data on its long-term oncological outcomes remain limited. Study aims to evaluate long-term efficacy and safety of focal IRE in patients with localized low- and intermediate-risk PCa. Methods This prospective single-center study enrolled patients with PCa (ISUP 1-2, PSA <15 ng/ml, T1c-T2a) who underwent IRE with NanoKnife® between 2018 and 2022. Follow-up included functional assessments (IPSS, QoL, IIEF-5), PSA testing, MRI, and biopsy at 12 months, with a telephone survey conducted at 5-year follow-up. Results Twenty-three patients were enrolled. Validated functional assessments (IPSS, QoL, and IIEF-5) performed at 3 and 6 months after treatment showed no clinically significant deterioration.At 12 months, 15 patients had undergone biopsy: 6 (40%) had a clinically significant relapse, and 6 (40%) – clinically insignificant relapse. Long-term follow-up data (median 58.5 months) were available for 16 patients. 10 (62.5%) underwent salvage treatment. Histology after salvage RP was available for 6 patients and showed no relapse within the ablation zone in 5 patients and ISUP 2 grade PCa (both in-field and out-field) with perineural invasion in 1 patient. No long-term AEs or functional impairment was reported. Conclusions Short-term oncological assessment after IRE showing 40% of clinically significant relapse and 66.7% treatment success may not fully capture the subsequent clinical course, as 10/16 (62.5%) patients with available extended follow-up underwent salvage treatment. IRE is a safe procedure with no significant impact on urinary and sexual function at the first year. Subsequent long-term follow-up (median 58.5 months) did not reveal any patient-reported side effects or deterioration of functional outcomes. Despite good functional profile, oncological control remains challenging in this cohort. This is particularly important to consider for such patients who could otherwise be candidates for AS. Long-term follow-up, rigorous patient selection based on high-resolution multiparametric MRI and systematic biopsy, and optimization of ablation margins may help to improve outcomes.