Oncological and functional outcomes of focal irreversible electroporation for localised prostate cancer: a single institution series of 171 cases

BACKGROUND: Focal irreversible electroporation (IRE) is an attractive choice for patients aiming to obtain local control of prostate cancer, while decreasing the postoperative risk of impotence and incontinence compared to whole-gland treatments. METHODS: Retrospective review of a single centre prospective database of 171 consecutive primary IRE procedures for localised prostate cancer. Primary outcomes include oncological infield and out-of-field progression. Secondary objectives include post-IRE continence and impotence. RESULTS: The median follow-up is 35 months (3-90 months). The median diameter of the treated lesions is 11 mm (4-24 mm). Most patients had PI-RADS 4-5 abnormalities on prostate MRI, and 25 patients (15%) had ISUP grade 4-5 cancer. Of the 135 patients with >12 months follow-up, 84 had a surveillance biopsy of whom 8.3% had significant infield persistence, with significant out-of-field cancer in 14.3%. There was no difference in the risk of infield cancer persistence regardless of the pre-IRE ISUP score (p = 0.8), or tumour location (p > 0.9). The presence of low volume out-of-field cancer at diagnosis did not increase the risk of post-IRE cancer persistence/progression (p = 0.7). The prostate PSMA PET SUVmax of ≥10 did not increase the risk of infield or out-of-field recurrence of cancer (p = 0.3). A PSAD > 0.15 did not increase the risk of infield persistence or out-of-field progression of cancer (p = 0.8). Urinary continence was maintained in 167/171 (97.6%), while erectile function was maintained in 94/112 (84%) of sexually active patients who completed questionnaires. CONCLUSIONS: Of the patients who proceeded to post-IRE biopsy, 92% had infield ablation of clinically significant cancer with a low risk of urinary incontinence or impotence. Focal IRE of prostate cancer has promising short to medium-term outcomes and is associated with low risks of impotence and incontinence. Long-term follow-up of out-of-field progression risk is required.