Prostate focal therapy: the rule or exception?

Established focal therapy-HIFU, IRE, or cryotherapy-where are we now?-a systematic review and meta-analysis

INTRODUCTION

Focal Therapy (FT) is a treatment option for the treatment of limited volume clinically significant prostate cancer (csPCa). We aim to systematically review outcomes of established FT modalities to assess the contemporary baseline and identify gaps in evidence that will aid in further trial and study design.

METHODS

We conducted a systematic review and meta-analysis of all primary studies reporting outcomes of FT using cryotherapy, high-intensity focused ultrasound (HIFU), and irreversible electroporation (IRE). We described patient inclusion criteria, selection tools, treatment parameters, and surveillance protocols, and pooled overall survival (OS), cancer-specific survival (CSS), metastasis-free survival (MFS), biochemical progression (BP), biopsy, secondary treatment, sexual, and urinary function outcomes. Composite failure was defined as salvage whole gland ablation, radical treatment, hormonal therapy or transition to watchful waiting.

SYNTHESIS

We identified 49 unique cohorts of men undergoing FT between 2008 and 2024 (21 cryotherapy, 20 HIFU, and 8 IRE). Median follow-up ranged from 6 to 63 months. Pooled OS was 98.0%, CSS 99.3%, and MFS 98.5%. Pooled BP was 9.4%/year. Biopsy was mandated post-FT within 24 months in 36/49 (73.5%) cohorts, with pooled csPCa (GG ≥ 2) rates of 22.2% overall, 8.9% infield, and 12.3% outfield. The pooled rate of secondary FT was 5.0%, radical treatment 10.5%, and composite failure 14.1%. Of 35 studies reporting sexual function, 45.7% reported a low, 48.6% moderate, and 5.7% severe impact. For 34 cohorts reporting urinary function, 97.1% reported a low impact. No differences were noted between cryotherapy, HIFU, or IRE in any of the outcomes.

CONCLUSION

FT with cryotherapy, HIFU, and IRE is associated with good short-intermediate term oncological and functional outcomes. However, outcome reporting is heterogeneous and often incomplete. Long-term follow-up and standardized reporting are required to better define and report FT outcomes.

Biopsy and Erectile Functional Outcomes of Partial Prostate Ablation: A Systematic Review and Meta-analysis of Prospective Studies

OBJECTIVE

To provide a systematic summary of prospectively performed studies evaluating ablative therapies for the treatment of prostate cancer (PCa) that included protocol-mandated assessment of (1) residual disease by post-treatment biopsy and/or (2) erectile functional outcomes.

MATERIALS AND METHODS

We performed a comprehensive literature search in September 2022. Studies were evaluated according to a predefined and registered plan in PROSPERO (CRD42022302777). Only prospective trials with protocol-mandated post-treatment prostate biopsies or functional assessments were included. Targeted focal therapy was the only ablation pattern with sufficient data to perform meta-analyses (29 studies, 1079 patients).

RESULTS

At baseline, 65.0% of patients treated with targeted focal therapy harbored grade group (GG) ≥2 PCa. One year after treatment, in-field treatment failure with ≥GG1 and ≥GG2 PCa occurred in 25.7% (range 11.1%-66.7%) and 8.8% (range 0%-27.8%) of men, respectively. In patients that received whole-gland biopsies 1year after ablation, residual ≥GG1 and ≥GG2 PCa was detected anywhere in the prostate in 43.7% (range 19.4%-71.7%) and 13.0% (range 0%-35.9%) of men. Erectile function was negatively affected by treatment, but 78.7% were potent 1year after targeted focal therapy (7 studies, 197 patients), and the average decrease in erectile function scores was 8.8% at 1year (21 studies, 760 patients).

CONCLUSION

Though long-term data after targeted focal therapy are limited, oncologic and treatment failure occurred in 13% and 9% (≥GG2 at 6-12months after treatment). Most men were able to maintain potency. This work can help benchmark new techniques and power future trials.

Defining prostate cancer size and treatment margin for focal therapy: does intralesional heterogeneity impact the performance of multiparametric MRI?

OBJECTIVES

To evaluate the impact of intralesional heterogeneity on the performance of multiparametric magnetic resonance imaging (mpMRI) in determining cancer extent and treatment margins for focal therapy (FT) of prostate cancer.

PATIENTS AND METHODS

We identified men who underwent primary radical prostatectomy for organ- confined prostate cancer over a 3-year period. Cancer foci on whole-mount histology were marked out, coding low-grade (LG; Gleason 3) and high-grade (HG; Gleason 4-5) components separately. Measurements of entire tumours were grouped according to intralesional proportion of HG cancer: 0%, <50% and ≥50%; the readings were corrected for specimen shrinkage and correlated with matching lesions on mpMRI. Separate measurements were also taken of HG cancer components only, and correlated against entire lesions on mpMRI. Size discrepancies were used to derive the optimal tumour size and treatment margins for FT.

RESULTS

There were 122 MRI-detected cancer lesions in 70 men. The mean linear specimen shrinkage was 8.4%. The overall correlation between histology and MRI dimensions was r = 0.79 (P < 0.001). Size correlation was superior for tumours with high burden (≥50%) compared to low burden (<50%) of HG cancer (r = 0.84 vs r = 0.63; P = 0.007). Size underestimation by mpMRI was more likely for larger tumours (51% for >12 mm vs 26% for ≤12 mm) and those containing HG cancer (44%, vs 20% for LG only). Size discrepancy analysis suggests an optimal tumour size of ≤12 mm and treatment margins of 5-6 mm for FT. For tumours ≤12 mm in diameter, applying 5- and 6-mm treatment margins would achieve 98.6% and 100% complete tumour ablation, respectively. For tumours of all sizes, using the same margins would ablate >95% of the HG cancer components.

CONCLUSIONS

Multiparametric MRI performance in estimating prostate cancer size, and consequently the treatment margin for FT, is impacted by tumour size and the intralesional heterogeneity of cancer grades.