559 - MR-guided Cryoablation in the Treatment of Recurrent Prostate Cancer in the Prostate Bed: A 13-Year Prospective Study

Purpose: To assess the efficacy, safety, and functional outcomes of MR-guided cryoablation for treating prostate bed recurrent prostate cancer.

Materials and Methods: In this IRB-approved study, 94 patients with recurrent prostate cancer, previously treated with radiotherapy or prostatectomy, underwent MR-guided cryoablation between September 2011 and September 2024. The mean patient age was 73 years (range: 60–89). Procedures typically used four cryoneedles (range: 3–6) with three freeze/thaw cycles, along with a urethral warmer for protection. T2-weighted MRI sequences (~20 sec) were used to monitor iceball formation and target coverage. PSA levels were recorded pre-ablation and at 6 and 12 months post-procedure. Follow-up included PSA testing and imaging (PET PSMA, PET 11-C Choline, or MRI) every 3 ± 1 months for 24 months. Functional outcomes were evaluated using validated questionnaires (AUASS, SHIM, and EPIC) at baseline and follow-up.

Results: Mean pre-ablation PSA was 3.57 ± 4.38, decreasing to 1.41 ± 3.70 at 6 months and 1.52 ± 4.88 at 12 months, representing PSA reductions of 60.5% (p < 0.001) and 57.5% (p < 0.001), respectively. In-field recurrence occurred in 12 patients (12.7%) after an average of 2.1 years, while 23 patients (24.4%) developed new lesions outside the treatment field. Overall, 35 patients (37.2%) experienced recurrence (in-field or out-of-field), with a mean recurrence-free period of 2.6 years (range: 1–11).
Functional outcomes were available in 58 patients. Urinary function remained stable, with no significant change in AUASS (9.9±7.1 vs. 9.7±7.9, p=0.84), pad use, or EPIC urinary bother scores. However, sexual function declined significantly, with SHIM decreasing from 8.1±8.0 at baseline to 4.5±6.4 post-ablation (p=0.002), accompanied by a rise in EPIC sexual bother scores (1.8±1.6 to 2.5±1.6, p=0.01).

Conclusion: MRI-guided focal cryoablation is an effective and safe treatment for recurrent prostate cancer, providing significant and sustained PSA reductions and prolonged recurrence-free intervals. The procedure preserved urinary function and continence but was associated with a measurable decline in sexual function, consistent with salvage settings. MRI guidance allows precise targeting and monitoring, supporting its role as a valuable salvage therapy option.