This is a prospective single center ongoing study, conducted between 2016 and 2023, with 113 patients who underwent focal HIFU treatment for PC. Follow-up included prostate-specific antigen (PSA) measurement every 3 mo, magnetic resonance imaging, and a control biopsy performed at 6 or 12 mo. Recurrence was categorized on the basis of location (infield or out-of-field) and Gleason grade group (clinically significant [CS] vs non-CS) with stratification by National Comprehensive Cancer Network risk groups. Kaplan-Meier curves were used to analyze survival outcomes, recurrence rates, and the need for retreatment.
The median follow-up was 29 mo and 92 patients (81%) had PSA follow-up for at least 12 mo. There was local recurrence in 34 patients (37%), and CS in 16 (17%). The CS recurrence–free survival rate at 3 yr was worse for subgroups with high-risk or unfavorable intermediate-risk disease compared to the group with favorable intermediate-risk PC (40% and 53% vs 85%; log-rank p < 0.01). Analysis by recurrence field revealed significant differences among NCCN risk groups for out-of-field recurrences (Fig. 1C), with a worse RFS rate for the high-risk group (log-rank p = 0.014). The Kaplan-Meier retreatment-free survival rate estimate was 71% at 3 yr (Fig 1).
Figure 1: Kaplan Meier curves for survival free from recurrence of clinically significant prostate cancer after high-intensity focused ultrasound, stratified by baseline NCCN risk category (A) regardless of field of recurrence, (B) for infield recurrences, and (C) for out-of-field recurrence. (D) Kaplan Meier curve analysis for retreatment-free survival in the overall cohort and stratified by NCCN risk group according to product-limit estimates. The p values are from log-rank tests and numbers of patients at risk are shown by values above the y-axis. NCCN = National Comprehensive Cancer Network.
The high-risk group had a higher rate of clinically significant out-of-field recurrence (27%) than the other risk groups. The rate of clinically significant infield recurrence was higher in the unfavorable intermediate-risk group (26%) than in the favorable intermediate-risk group (9%). Most infield recurrences were detected at the prostate apex (42%), whereas outfield recurrences were similarly distributed.
While infield recurrences can mainly be attributed to technique failure in the ablation of tumor tissue, out-of-field recurrences occur because of tumor multifocality and poor patient selection.
In conclusion, the characterization of post-HIFU recurrence patterns is essential for evaluating therapeutic efficacy and informing subsequent salvage interventions when necessary. HIFU is a promising alternative for localized PC in well-selected patients. However, patients with high-risk or unfavorable intermediate-risk PC are more likely to experience treatment failure.
Written by:
- Tarek Ajami, MD, Desai Sethi Urology Institute, Miller School of Medicine, University of Miami, Miami, FL; Department of Urology, Hospital Clinic de Barcelona, University of Barcelona, Barcelona, Spain
- Bruno Nahar, MD, Desai Sethi Urology Institute, Miller School of Medicine, University of Miami, Miami, FL
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