Novel MRI-US fusion with advanced annotation in focal cryoablation for prostate cancer: medium-term outcomes and learning curve insights.

OBJECTIVES

To assess the oncological and functional outcomes of magnetic resonance imaging-ultrasonography (MRI-US) fusion-guided focal cryoablation (FC) using a novel three-dimensional Advanced Annotation Platform (AAP) in patients with localised prostate cancer (PCa) and compare results between expert and beginner surgeons to evaluate the impact of prior focal therapy (FT) experience on FT outcomes.

PATIENTS AND

METHODS

A prospective single-arm trial enrolled 50 men with low- to intermediate-risk PCa who underwent FC between December 2020 and September 2023. MRI-US fusion-guided FC was performed using the UroNav AAP by two surgeons with different FT experience (>200 vs 0), with 19 cases carried out by an expert and 31 by a beginner surgeon. Follow-up included prostate-specific antigen, multiparametric MRI, and protocol biopsy at 1 year. The primary outcome was failure-free survival (FFS), defined as the transition to radical salvage treatment or to systemic therapy, development of PCa metastases, or PCa-specific death. Secondary outcomes included oncological control and functional outcomes. Post hoc analyses were performed to assess learning curves and compare outcomes between surgeons with different experience levels.

RESULTS

The 2-year FFS was 96% (95% confidence interval [CI] 90.7-100%). The 1-year protocol biopsy showed a 6% in-field (IFR) and 12% out-of-field recurrence (OFR) rates. Urinary function fully recovered at 3 months. Among men with baseline Sexual Health Inventory for Men score ≥17, 85% recovered erectile function at 1 year, with baseline function as the main predictor of recovery at 1 year. All complications (26%) were Common Terminology Criteria for Adverse Events Grade 1-2. There was no significant difference in FC outcomes between surgeons. Learning curves were demonstrated primarily for ablation time with a decrease of 1.44 min per case (95% CI -1.98 to -0.90), with small effects for number of cryoprobes (0.041 decrease per case, 95% CI -0.067 to -0.014) and OFR rate (0.014 decrease per case, 95% CI -0.028 to -0.0003), but not for the IFR rate and complications. No differences in learning patterns were observed between surgeons.

CONCLUSION

Fusion-guided FC using the UroNav AAP demonstrated good oncological control and safety profile. The device allowed precise MRI-US fusion-guided treatment while minimising the learning curve difference between expert and beginner surgeons.