Extra-target low-risk prostate cancer: implications for focal high-intensity focused ultrasound of clinically significant prostate cancer

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.

Focal therapy of localized prostate cancer

In the treatment of localized prostate cancer, controlling the cancer and maintaining quality of life are important. Focal therapy of localized prostate cancer aims to treat the lesion/part of the prostate that includes the index lesion, which determines the prognosis. We performed a non-systematic review of novel studies on focal therapy of localized prostate cancer as primary treatment published between 2016 and 2021. For mainly intermediate-risk patients, therapeutic technology, such as cryoablation, brachytherapy, high-intensity focused ultrasound, photodynamic therapy, microwave-coagulation, electroporation, and laser ablation, etc., were performed. These procedures are minimally invasive and safe, and provide good functional outcome: a 94-100% pad-free rate against urinary incontinence and 47-86% erectile function, which is sufficient for sexual intercourse. Accurate three-dimensional mapping of the targeted lesion could be an essential navigation technique for therapeutic success. Intermediate- to short-term oncological outcomes were good, resulting in downstaging of the patient's status to no clinically significant cancer; however, transition to conventional whole-gland treatment was necessary in about 10-30% of patients. It is important to select appropriate patients by both multiparametric magnetic resonance imaging and targeted biopsy, and to follow-up postoperatively with methods such as active surveillance. Clinically significant prostate-specific antigen reduction, image response using preoperative and postoperative multiparametric magnetic resonance imaging, and histological analysis should be combined for follow-up.

Tumour microenvironment and focal therapy for prostate cancer

PURPOSE OF REVIEW

Although most studies focus on the tumour component of prostate cancer (PCa), increasing attention is being paid to the prostatic tumour microenvironment (TME) and its role in diagnosis, prognosis, and therapy development. Herein, we review the prognostic capability of tumour and nontumour derived biomarkers, the immunomodulatory effects of focal therapy (FT) on TME, and its potential as part of a multidisciplinary approach to PCa treatment.

RECENT FINDINGS

Tumour cells have always been the natural candidates to explore new biomarkers, but recent evidence highlights the prognostic contribution of TME cell markers. TME plays a critical role in PCa progression and tumours may escape from the immune system by establishing a microenvironment that suppresses effective antitumour immunity. It has been demonstrated that FT has an immunomodulatory effect and may elicit an immune response that can either favour or inhibit tumorigenesis. TME shows to be an additional target to enhance oncological control.

SUMMARY

A better understanding of TME has the potential to reliably elucidate PCa heterogeneity and assign a prognostic profile in accordance with prostate tumour foci. The joint contribution of biomarkers derived from both tumour and TME compartments may improve patient selection for FT by accurately stratifying disease aggressivity according to the characteristics of tumour foci. Preclinical studies have suggested that FT may act as a TME modulator, highlighting its promising role in multimodal therapeutic management.

Focal prostate cancer therapy in the era of multiparametric MRI: a review of options and outcomes

BACKGROUND

The goal of prostate cancer focal therapy is to achieve oncologic control while reducing the rate of adverse events associated with whole-gland treatments. Numerous focal therapy modalities are currently available with early data demonstrating highly variable rates of cancer control and preservation of sexual/urinary function.

METHODS

All English language clinical trial publications evaluating various focal therapies for localized prostate cancer were reviewed. The literature search was limited to studies from the modern era of MRI-guided treatment, as MRI is hypothesized to improve tumor localization and targeting. Primary outcomes were post-treatment cancer-free rates, in-field/out-of-field recurrence rates, and rates of conversion to radical therapy. Secondary outcomes were related to functional status and adverse events.

RESULTS

Numerous focal therapies were identified with clinical data including high-intensity focused ultrasound, transurethral ultrasound ablation, focal laser ablation, focal cryotherapy, irreversible electroporation, and photodynamic therapy. Recurrence rates among all technologies were low to moderate (0-51%) and rates of freedom from radical treatment were highly variable (46-98%). Rates of erectile dysfunction and incontinence generally ranged from 0 to 44% and 0 to 12%, respectively, with variability between focal therapy modalities. Caution should be exercised when comparing studies as outcomes are strongly associated with patient selection. No individual focal therapy is currently recommended by society guidelines. Randomized controlled trials are ongoing in search of a standard of care.

CONCLUSION

For localized MRI-visible prostate cancer, early clinical trial data demonstrate that focal therapy can provide good to moderate cancer control while having preferable side effect profiles compared to whole-gland treatments. While current studies do not make head-to-head comparisons between technologies, early data suggest a potential for these technologies to provide adequate cancer control in a well-selected patient population. The oncologic outcomes of some focal therapies appear promising; however, longer-term follow-up data are needed to assess the durability of early outcomes.

Available evidence on HIFU for focal treatment of prostate cancer: a systematic review

PURPOSE

Prostate cancer (PCa) is the second most common oncologic disease among men. Radical treatment with curative intent provides good oncological results for PCa survivors, although definitive therapy is associated with significant number of serious side-effects. In modern-era of medicine tissue-sparing techniques, such as focal HIFU, have been proposed for PCa patients in order to provide cancer control equivalent to the standard-of-care procedures while reducing morbidities and complications. The aim of this systematic review was to summarise the available evidence about focal HIFU therapy as a primary treatment for localized PCa.

MATERIAL AND METHODS

We conducted a comprehensive literature review of focal HIFU therapy in the MEDLINE database (PROSPERO: CRD42021235581). Articles published in the English language between 2010 and 2020 with more than 50 patients were included.

RESULTS

Clinically significant in-field recurrence and out-of-field progression were detected to 22% and 29% PCa patients, respectively. Higher ISUP grade group, more positive cores at biopsy and bilateral disease were identified as the main risk factors for disease recurrence. The most common strategy for recurrence management was definitive therapy. Six months after focal HIFU therapy 98% of patients were totally continent and 80% of patients retained sufficient erections for sexual intercourse. The majority of complications presented in the early postoperative period and were classified as low-grade.

CONCLUSIONS

This review highlights that focal HIFU therapy appears to be a safe procedure, while short-term cancer control rate is encouraging. Though, second-line treatment or active surveillance seems to be necessary in a significant number of patients.

Clinical application of the therapeutic ultrasound in urologic disease: Part II of the therapeutic ultrasound in urology

This article aimed to review the clinical application and evidence of the therapeutic ultrasound in detail for urological diseases such as prostate cancer, kidney tumor, erectile dysfunction, and urolithiasis. We searched for articles about high-intensity focused ultrasound (HIFU), extracorporeal shock wave therapy, ultrasound lithotripsy, and extracorporeal shockwave lithotripsy (ESWL) in the MEDLINE and Embase. HIFU may be indicated as a primary treatment for low- or intermediate-risk prostate cancer, and salvage therapy for local recurrence as a promising way to address the limitations of current standard therapies. The application of HIFU in treating kidney tumors has scarcely been reported with unsatisfactory results. Evidence indicates that low-intensity shockwave therapy improves subjective and objective erectile function in patients with erectile dysfunction. Regarding the application of ultrasound in stone management, the novel combination of ultrasound lithotripsy and other energy sources in a single probe promises to be a game-changer in efficiently disintegrating large kidney stones in percutaneous nephrolithotomy. ESWL is losing its role in managing upper urinary tract calculi worldwide. The burst-wave lithotripsy and ultrasound propulsion could be the new hope to regain its position in the lithotripsy field. According to our investigations and reviews, cavitation bubbles of the therapeutic ultrasound are actively being used in the field of urology. Although clinical evidence has been accumulated in urological diseases such as prostate cancer, kidney tumor, erectile dysfunction, and lithotripsy, further development is needed to be a game-changer in treating these diseases.

An Updated Systematic Review on Focal Therapy in Localized Prostate Cancer: What Has Changed over the Past 5 Years?

CONTEXT

Focal therapy is a promising, minimally invasive strategy to selectively treat localized prostate cancer. A previous systematic review indicated that there is growing evidence for favorable functional outcomes, but that oncological effectiveness was yet to be defined.

OBJECTIVE

To assess the effectiveness of focal therapy in patients with localized prostate cancer in terms of functional and oncological outcomes.

EVIDENCE ACQUISITION

PubMed, Embase, and The Cochrane Library were searched for studies between October 2015 and December 31, 2020. In addition, the research stages were acquired according to the Idea, Development, Exploration, Assessment, Long-term study (IDEAL) recommendations. Ongoing studies were identified through clinical trial registries.

EVIDENCE SYNTHESIS

Seventy-two studies were identified exploring eight different sources of energy to deliver focal therapy in 5827 patients. Twenty-seven studies reported on high-intensity focused ultrasound (HIFU), nine studies on irreversible electroporation, 11 on cryoablation, eight on focal laser ablation and focal brachytherapy, seven on photodynamic therapy (PDT), two on radiofrequency ablation, and one on prostatic artery embolization. The majority of studies were prospective development stage 2a studies (n = 35). PDT and HIFU, both in stage 3, showed promising results. Overall, HIFU studies reported a median of 95% pad-free patients and a median of 85% patients with no clinically significant cancer (CSC) in the treated area. For PDT, no changes in continence were reported and a median of 90% of patients were without CSC. Both treatments were well tolerated.

CONCLUSIONS

Over the past 5 yr, focal therapy has been studied for eight different energy sources, mostly in single-arm stage 2 studies. Although a first randomized controlled trial in focal therapy has been performed, more high-quality evaluations are needed, preferably via multicenter randomized controlled trials with long-term follow-up and predefined assessment of oncological and functional outcomes and health-related quality-of-life measures.

PATIENT SUMMARY

Focal treatment (FT) of prostate cancer has potential, considering that it has less impact on continence and potency than radical treatment. Our systematic review indicates that despite the method being studied extensively over the past half decade, the majority of studies remain in an early research stage. The techniques high-intensity focused ultrasound and photodynamic therapy have shown most progression toward advanced research stages and show favorable results. However, more high-quality evidence is required before FT can become available as a standard treatment.

Current evidence for focal therapy and partial gland ablation for organ-confined prostate cancer: systematic review of literature published in the last 2 years

PURPOSE OF REVIEW

The shift in the diagnostic algorithm for prostate cancer to early imaging with mpMRI has resulted in many patients being diagnosed with small volume, apparently unilateral, clinically significant cancers. In these patients, a minimally invasive, nonmorbid intervention is appealing. The aim of this study was to review data reported within the last 2 years on focal therapy and partial gland ablation for organ-confined prostate cancer.

RECENT FINDINGS

High-intensity focal ultrasound, focal cryotherapy, photodynamic therapy, irreversible electroporation and focal laser ablation, have been used as treatment modalities for localized prostate cancer treatment. The reported oncologic outcomes vary widely and makes comparisons challenging. All the focal therapies report low rates of complications, and high rates of continence and erectile function preservation. The most common adverse events are hematuria, urinary retention and urinary tract infections. During this period, the initial results of several new technologies including MRI-guided transurethral ultrasound ablation were published.

SUMMARY

Focal therapy and partial gland ablation for organ-confined prostate cancer is an option for patients with intermediate-risk disease because of its low complication profile and preservation of QOL. Trials comparing the outcome of different focal therapy technologies have not been carried out, and the existing evidence does not point to one approach being clearly superior to others. Long-term oncologic outcome is lacking. Despite this, for men with unilateral intermediate-risk prostate cancer whose disease is often relatively indolent, focal therapy is an appealing option.

Should we perform systematic biopsies in case of suspicious MRI for prostate cancer in 2020? A review of literature

CONTEXT

Multiparametric magnetic resonance imaging (MRI) is now recommended before performing prostate biopsies, looking for suspicious lesions to perform targeted biopsies (TB). However, the association or exclusive performance of systematic biopsies (SB), criticized for its morbidity and for the detection of insignificant cancers, remains debated.

OBJECTIVE

To perform a literature review to answer three questions: (1) In the presence of a suspicious MRI lesion, should we always perform SB in addition to TB? (2) Can we avoid SB when considering focal treatment? (3) Is there an increase in adverse events when associating SB with TB?

SOURCES

A non-systematic literature review was carried out on Medline in April 2020 using the keywords "MRI", "PROSTATE CANCER", "SYSTEMATIC BIOPSY", "TARGETED BIOPSY", "ADVERSE EVENTS". The references of the selected articles were analyzed for additional articles. Selection of Studies published in the last five years were analyzed and retained if the available data made it possible to answer one of the three questions asked.

RESULTS

In biopsy-naive patients, the added value of SB to TB for detection of significative cancer varied from +5 to+7% and was reduced to +1 to +3% in the case of a previous series of negative biopsies. For patients under active surveillance, this added value was higher, ranging from +8% to +17%. MRI has a negative predictive value of 85 to 95%, but this value drops to 55% for the detection of secondary or tertiary foci. The use of SB is necessary if focal treatment is considered. Serious complications from biopsies requiring hospitalization range from 1.4 to 6.9% and are increased by the number of previous biopsy series performed more than by the number of biopsies per series.

CONCLUSION

In the presence of a suspicious MRI lesion, SB is indicated in addition to TB but can be discussed in patients with previous negative biopsies. They are necessary if focal treatment is considered to aid surgical planning. Severe complications from biopsies do not seem to increase when SB are associated to TB, but rather with the number of biopsy series performed.

The primary treatment of prostate cancer with high-intensity focused ultrasound: A systematic review and meta-analysis

BACKGROUND

We systematically evaluated the evidences on oncological and functional outcomes of high-intensity focused ultrasound (HIFU) as the primary treatment for localized prostate cancer (PCa).

METHODS

A systematic review was used Medline, Embase, and the Cochrane Library from the inception of each database. The review analyzed the oncological and functional outcomes of HIFU in the treatment of PCa. The RevMan 5.3 software was used for quantity analysis incidence of complications.

RESULTS

Twenty-seven articles were included for analysis with a total of 7393 patients. Eighteen studies investigated the whole-gland HIFU, and the duration of follow-up ranged from 2 to 168 months. After whole-gland HIFU, the mean prostate-specific antigen (PSA) nadir was found to be 0.4 to 1.95 ng/mL and the mean time to PSA nadir was 2.4 to 5.4 months. The rate of positive biopsy after HIFU was 4.5% to 91.1%. Meta-analysis revealed the incidences of urinary incontinence, impotence, urinary obstruction, retention, and infection was 10%, 44%, 15%, 11%, 7%, respectively. Nine studies investigated partial-gland HIFU, and the duration of follow-up was 1 to 131 months. After partial-gland HIFU, the mean PSA nadir was 1.9 to 2.7 ng/mL and the mean time to PSA nadir 5.7 to 7.3 months. The rate of positive biopsy after HIFU in the treatment area was 14% to 37.5%. Meta-analysis revealed the incidences of urinary incontinence, impotence, urinary obstruction, retention, and infection was 2%, 21%, 2%, 9%, 11%, respectively.

CONCLUSIONS

Early evidence suggested the partial-gland HIFU was safer than whole-gland HIFU, and they had similar oncological outcomes. More prospective randomized controlled trials of whole-gland and partial-gland HIFU for PCa was needed.