Current state of image-guided focal therapy for prostate cancer

Magnetic resonance imaging-ultrasound fusion guided focal cryoablation for men with intermediate-risk prostate cancer

INTRODUCTION

Focal therapy (FT) is a form of ablative treatment offered to men with localized, organ-confined prostate cancer (CaP). Pelvic multiparametric magnetic resonance imaging (mpMRI) and mpMRI/transrectal ultrasound fusion (MRI-US) guidance enable the precise delivery of FT with limited ablation of adjacent benign tissue or vital genitourinary structures. This article presents our findings on using MRI-US to perform FT as a primary treatment for men with intermediate-risk CaP.

METHODS

Thirty-six men underwent MRI-US fusion-guided FT cryoablation at a single center from 2018 to 2023 as a primary treatment for intermediate-risk CaP. Following FT, quarterly prostate-specific antigen (PSA) testing and a 6 to 9 month mpMRI and combined MRI-US targeted and systematic biopsy were performed. Oncological outcomes were determined using several endpoints containing biochemical recurrence, imaging failure, and pathological failure. Functional outcomes were measured using reported erectile dysfunction/potency rates, urinary incontinence rates, and the American Urologic Association Symptom Score (AUA-SS) and Sexual Health Inventory for Men (SHIM) indices.

RESULTS

Median follow-up was 29.1 months, most (75%) of whom had grade group 2 CaP. Out of the 36 men, 32 (88.9%) completed the combined MRI-targeted and systematic biopsy follow-up after treatment. The study had no major complications, but 12 (33.3%) patients experienced Clavien-Dindo grade II or lower complications. For oncological outcomes, 6 (16.7%) men had biochemical recurrence, 9 (25%) showed imaging failure, and 8 (22.2%) met the criteria for positive biopsy- out-of-field vs. in-field. 88.2% of previously potent patients remained potent postoperatively at 12 months. All patients were continent at 12 months. There were no statistically significant changes in the AUA-SS and SHIM scores postoperatively.

CONCLUSION

MRI-US-guided cryoablation to target lesions in intermediate-risk CaP appears to be a safe treatment option, with functional outcomes indicating minimal short and intermediate-term morbidity and acceptable oncological outcomes. However, despite close monitoring and follow-up, there is still a limitation in accurately predicting/detecting pathological failure after FT. The long-term durability of FT for intermediate-risk, organ-confined CaP remains uncertain.

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.

Prostate Cancer IRE Study (PRIS): A Randomized Controlled Trial Comparing Focal Therapy to Radical Treatment in Localized Prostate Cancer

The aim of focal treatments (FTs) in prostate cancer (PCa) is to treat lesions while preserving surrounding benign tissue and anatomic structures. Irreversible electroporation (IRE) is a nonthermal technique that uses high-voltage electric pulses to increase membrane permeability and induce membrane disruption in cells, which potentially causes less damage to the surrounding tissue in comparison to other ablative techniques. We summarize the study protocol for the Prostate Cancer IRE Study (PRIS), which involves two parallel randomized controlled trials comparing IRE with (1) robot-assisted radical prostatectomy (RARP) or (2) radiotherapy in men with newly diagnosed intermediate-risk PCa (NCT05513443). To reduce the number of patients for inclusion and the study duration, the primary outcomes are functional outcomes: urinary incontinence in study 1 and irritative urinary symptoms in study 2. Providing evidence of the lower impact of IRE on functional outcomes will lay a foundation for the design of future multicenter studies with an oncological outcome as the primary endpoint. Erectile function, quality of life, treatment failure, adverse events, and cost effectiveness will be evaluated as secondary objectives. Patients diagnosed with Gleason score 3 + 4 or 4 + 3 PCa from a single lesion visible on magnetic resonance imaging (MRI) without any Gleason grade 4 or higher in systematic biopsies outside of the target (unifocal significant disease), aged ≥40 yr, with no established extraprostatic extension on multiparametric MRI, a lesion volume of <1.5 cm³, prostate-specific antigen <20 ng/ml, and stage ≤T2b are eligible for inclusion. The study plan is to recruit 184 men.

Assessment after focal therapy: what is the latest?

PURPOSE OF REVIEW

To review assessment after focal therapy (FT) in the context of developments from the past two years.

RECENT FINDINGS

With a paucity of high-quality studies, recent findings are primarily reliant on results from institutional-based cohorts and reports of expert consensus. Notably, oncologic treatment failure should be further stratified into recurrence in the in-field or out-of-field ablation zone, and both regions should be surveilled postoperatively. Monitoring primarily consists of periodic evaluations of prostate-specific antigen (PSA) testing and magnetic resonance imaging, with histologic sampling needed to confirm suspicion of recurrence. Recent investigations into PSA derivatives, contrast-enhanced ultrasound, and prostate-specific membrane antigen imaging have shown preliminary promise. Although postablation functional outcomes are generally accepted to be excellent, they are limited by the wide range of patient-reported measures, variability in individual practice, and low questionnaire completion rates.

SUMMARY

There is still a need for high-level, long-term data to inform exact standardized protocols to manage patients after FT. A multifaceted approach is required to surveil patients and identify those at risk of recurrence. Embracing shared responsibility between the patient and clinician to fastidiously monitor the infield and out-of-field ablation zones postoperatively is critical to maximize oncologic outcomes.

Ablative options for prostate cancer management

This review provides an overview of the available ablative options for prostate cancer (PCa) management. It contemplates the ablative concepts and the role of prostate ablation in different settings, from primary treatment to repeat ablation, and as an alternative to radiorecurrent disease. Improvements in prostate imaging have allowed us to ablate prostate lesions through thermal, mechanical, and vascular-targeted sources of energy. Partial gland ablation (PGA) has an emerging role in the management of localized PCa because toxicity outcomes have been proven less harmful compared with whole-gland treatments. Although long-term oncological outcomes are yet to be consolidated in comparative studies, recent large series and prospective studies in PGA have reported encouraging results. A second ablation after disease recurrence has demonstrated low toxicity, and future studies must define its potential to avoid radical treatments. PGA is an attractive option for PCa management in different scenarios because of its low-toxicity profile. As expected, recurrence rates are higher than those seen in whole-gland procedures. Long-term oncological outcomes of primary and salvage options are required to endorse it among the standard treatments.