Complications, Recovery, and Early Functional Outcomes and Oncologic Control Following In-bore Focal Laser Ablation of Prostate Cancer

Oncological results and cancer control definition in focal therapy for Prostate Cancer: a systematic review

INTRODUCTION

Focal therapy (FT) is a promising alternative to whole-gland treatments for Localized Prostate Cancer. Ten different FT modalities have been described in literature. However, FT is not yet recommended by the International Guidelines, due to the lack of robust data on Oncological Outcomes. The objective of our Narrative Review is to evaluate the oncological profile of the available FT modalities and to offer a comprehensive overview of the definitions of Cancer Control for FT.

MATERIAL AND METHODS

Literature search was performed on 21st February 2023 using PubMed, EMBASE, and Scopus, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement (PRISMA). Articles reporting whole gland-treatments were excluded. All articles reporting oncological outcomes were included.

RESULTS

One-hundred-twenty-four studies, reporting data on more than 8000 patients treated with FT, were included. Overall, 40 papers were on High Intensity Focal Ultrasound (HIFU), 24 on Focal Cryotherapy, 13 on Irreversible Electroporation (IRE), 11 on Focal brachytherapy, 10 on Focal Laser Ablation (FLA), 8 on Photo-Dynamic Therapy (PDT), 3 on Microwave ablation, 3 on Robotic Partial Prostatectomy, 2 on bipolar Radio Frequency Ablation (bRFA), 1 on Prostatic Artery Embolization (PAE) and 9 comparative papers. Overall, the Biochemical Recurrence (BCR) rate ranged from 0% (Focal Brachytherapy) to 67.5% (HIFU); the Salvage treatment rate ranged from 1% (IRE) to 54% (HIFU) considering re-treatment with FT and from 0% (Focal Brachytherapy) to 66.7% considering standard Radical Treatments. There is no univocal definition of Cancer Control, however the "Phoenix criteria" for BCR were the most commonly used.

CONCLUSIONS

FT is a promising alternative treatment for localized prostate cancer in terms of Oncological Outcomes, however there is a wide heterogeneity in the definition of cancer control, the reporting of oncological outcomes and a lack of high-quality clinical trials. Solid comparative studies with standard treatments and an unambiguous consensus on how to describe Cancer Control in the field of Focal Therapy are needed.

Identifying the best candidate for focal therapy: a comprehensive review

BACKGROUND

Despite the evidence supporting the use of focal therapy (FT) in patients with localized prostate cancer (PCa), considerable variability exists in the patient selection criteria across current studies. This study aims to review the most recent evidence concerning the optimal approach to patient selection for FT in PCa.

METHODS

PubMed database was systematically queried for studies reporting patient selection criteria in FT for PCa before December 31, 2023. After excluding non-relevant articles and a quality assessment, data were extracted, and results were described qualitatively.

RESULTS

There is no level I evidence regarding the best patient selection approach for FT in patients with PCa. Current international multidisciplinary consensus statements recommend multiparametric magnetic resonance imaging (mpMRI) followed by MRI-targeted and systematic biopsy for all candidates. FT may be considered in clinically localized, intermediate risk (Gleason 3 + 4 and 4 + 3), and preferably unifocal disease. Patients should have an acceptable life expectancy. Those with prostate volume >50 ml and erectile dysfunction should not be excluded from FT. Prostate-specific antigen (PSA) level of < 20 (ideally < 10) ng/mL is recommended. However, the utility of other molecular and genomic biomarkers in patient selection for FT remains unknown.

CONCLUSIONS

FT may be considered in well-selected patients with localized PCa. This review provides a comprehensive insight regarding the optimal approach for patient selection in FT.

The Contemporary Role of Salvage Radical Prostatectomy in the Management of Recurrent Prostate Cancer: An Up-to-Date Review

Prostate cancer is the second most common cancer among men, with many treatment modalities available for patients, such as radical prostatectomy, external beam radiotherapy, brachytherapy, high-intensity focused ultrasound, cryotherapy, electroporation and other whole-gland or focal ablative novel techniques. Unfortunately, up to 60% of men with prostate cancer experience recurrence at 5 to 10 years. Salvage radical prostatectomy can be offered as an option in the setting of recurrence after a primary non-surgical treatment. However, the complexity of salvage radical prostatectomy is considered to be greater than that of primary surgery, making it the least popular treatment of choice. With the wide use of robotic platforms in urologic oncologic surgery, salvage radical prostatectomy has attracted attention again because, compared to past data, modern series involving salvage Robot-Assisted Radical Prostatectomy have shown promising results. In this narrative literature review, we comprehensively examined data on salvage radical prostatectomy. We investigated the correlation between the different types of primary prostate cancer therapy and the following salvage radical prostatectomy. Furthermore, we explored the concept of a robotic approach and its beneficial effect in salvage surgery. Lastly, we emphasized several promising avenues for future research in this field.

Transperineal Laser Ablation (TPLA) Treatment of Focal Low-Intermediate Risk Prostate Cancer

Background: This interventional pilot study aimed to evaluate the short-term (3 years) efficacy of focal laser ablation (FLA) in treating the index lesion of low-intermediate-risk prostate cancer, along with assessing the safety of the procedure (ClinicalTrials.gov ID NCT04045756). Methods: Forty patients aged between 46 and 86 with histologically proven organ-confined prostate cancer and low-to-intermediate progression risk were included. FLA was performed under percutaneous fusion magnetic resonance/ultrasound guidance in a Day Hospital setting under local anesthesia. Patients underwent regular clinical and functional assessments through the international index of erectile function (IIEF-5) and the International Prostatism Symptom Score (IPSS), PSA measurements, post-procedure MRI scans, and biopsies at 36 months or if positive findings were detected earlier. Statistical analyses were conducted to assess trends in PSA levels and cavity dimensions over time. Results: Forty patients were initially included, with fifteen lost to follow-up. At 36 months, a mean PSA reduction of 60% was observed, and 80% of MRI scans showed no signs of in-field clinically significant residual/recurrent cancer. Biopsies at 36 months revealed no malignant findings in 20 patients. No deterioration in sexual function or urinary symptoms was recorded. Conclusions: FLA appears to be safe, feasible, and effective in the index lesion treatment of low-intermediate-risk prostate cancer, with a high rate of tumor eradication and preservation of quality of life.

MRI-guided Minimally Invasive Focal Therapies for Prostate Cancer

Two cases involving patients diagnosed with localized prostate cancer and treated with MRI-guided focal therapies are presented. Patient selection procedures, techniques, outcomes, challenges, and future directions of MRI-guided focal therapies, as well as their role in the treatment of low- to intermediate-risk localized prostate cancer, are summarized.

Two Year Functional Outcomes Stratified According to Baseline Erectile Function Following Partial Gland Cryo-Ablation

OBJECTIVE

To critically evaluate time dependent sexual function following primary partial gland cryo-ablation (PGCA) stratified according to baseline erectile function.

METHODS

Between March 2017 and March 2022, all men undergoing primary PGCA by 2 surgeons were enrolled in an IRB approved outcomes registry. All subjects with PIRADS 2-5 lesion concordant with unilateral GGG 1-3 disease, no gross extra-prostatic extension on mpMRI, GGG >1 contralateral to the ROI, or distal apical disease on mpMRI were enrolled. Patients completed the Sexual Health Inventory for Men (SHIM) scale at baseline, 6, and 24 months. Men were stratified by baseline erectile function. Men with SHIM Score < 8 were excluded. Ability to sustain erection (aka "potency") was defined as a score of 3 or greater on question 2 of the SHIM index. Median SHIM scores and the proportion of men reporting "potency" at baseline, 6, and 24 months was recorded with comparisons between each timepoint. A univariate analysis was used to determine if clinical factors were associated with loss of "potency" at 24 months.

RESULTS

106 men met the inclusion criteria. There was a statistically significant decrease in the mean SHIM scores for the entire cohort between baseline to 6 months and baseline to 24 months. SHIM scores increased significantly for the total cohort between 6 and 24 months. "Potency" was preserved in 70% at 24 months.

CONCLUSION

Those patients most likely to exhibit a decrease in sexual function have moderate ED at baseline. Only baseline ED was shown to predict preservation of "potency".

MR Imaging in Real Time Guiding of Therapies in Prostate Cancer

Magnetic resonance imaging (MRI)-guided therapy for prostate cancer (PCa) aims to reduce the treatment-associated comorbidity of existing radical treatment, including radical prostatectomy and radiotherapy. Although active surveillance has been used as a conservative method to reduce overtreatment, there is a growing demand for less morbidity and personalized (focal) treatment. The development of multiparametric MRI was of real importance in improving the detection, localization and staging of PCa. Moreover, MRI has been useful for lesion targeting within the prostate, as it is used in the guidance of prostate biopsies, by means of cognitive registration, MRI-ultrasound fusion guidance or direct in-bore MRI-guidance. With regard to PCa therapies, MRI is used for precise probe placement into the lesion and to accurately monitor the treatment in real-time. Moreover, advances in MR-compatible thermal ablation allow for noninvasive real-time temperature mapping during treatment. In this review, we present an overview of the current status of MRI-guided therapies in PCa, focusing on cryoablation, focal laser ablation, high intensity focused ultrasound and transurethral ultrasound ablation. We explain the important role of MRI in the evaluation of the completeness of the ablation and during follow-up. Finally, we will discuss the challenges and future development inherent to these new technologies.

A systematic review of outcomes after thermal and nonthermal partial prostate ablation

We sought to compare oncologic and functional outcomes between thermal and nonthermal energy partial gland ablation (PGA) modalities. We conducted comprehensive, structured literature searches, and 39 papers, abstracts, and presentations met the inclusion criteria of pre-PGA magnetic resonance imaging, oncologic outcomes of at least 6 months, and systematic biopsies after PGA. Twenty-six studies used thermal ablation: high-intensity focused ultrasound (HIFU), cryotherapy, focal laser ablation, or radiofrequency ablation. In-field recurrence rates ranged from 0 to 36% for HIFU, 6 to 24% for cryotherapy, 4 to 50% for focal laser ablation, and 20 to 25% for radiofrequency ablation. Twelve studies used nonthermal technologies of focal brachytherapy, vascular-targeted photodynamic therapy, or irreversible electroporation. Focal brachytherapy had the lowest reported failure rate of 8%, vascular-targeted photodynamic therapy had >30% positive in-field biopsies, and irreversible electroporation had in-field recurrence rates of 12-35%. PGA was well tolerated, and nearly all patients returned to baseline urinary function 12 months later. Most modalities caused transient decreases in erectile function. Persistent erectile dysfunction was highest in patients who underwent HIFU. Although oncologic outcomes vary between treatment modalities, systematic review of existing data demonstrates that PGA is a safe treatment option for patients with localized prostate cancer.

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.

Unilateral lesion detected on preoperative multiparametric magnetic resonance imaging and MRI/US fusion-guided prostate biopsy is not an appropriate indication for focal therapy in prostate cancer

PURPOSE

This study aimed to investigate if preoperative assessments of multiparametric magnetic resonance imaging (mpMRI) and Magnetic resonance imaging /ultrasound (MRI/US) fusion-guided prostate biopsy could be used to guide focal therapy for prostate cancer.

MATERIALS AND METHODS

A total of 101 prostate cancer patients undergoing radical prostatectomy were included. Preoperative findings included mpMRI and MRI/US fusion-guided prostate biopsy, while postoperative whole mount pathology was based on surgical specimen.

RESULTS

Of the 101 patients preoperatively diagnosed with a unilateral tumor, postoperative whole mount pathology showed 73.27% were bilateral tumors, and 71.62% of bilateral lesions were clinically significant. Comparison between preoperative and postoperative findings, the correct rate of preoperative mpMRI on the lesion side (left or right) was only 20.79%. As for the Gleason score, the correct rate of preoperative MRI/US fusion-guided prostate pathology was 67.33%. Judging from postoperative whole mount pathology, 47.52% of patients had a unilateral clinically significant tumor, which is an indication for focal therapy.

CONCLUSION

Preoperative examinations of mpMRI and MRI/US fusion-guided prostate biopsy cannot be used to guide focal therapy for prostate cancer.

5-Year Outcomes Following Focal Laser Ablation of Prostate Cancer

OBJECTIVE

To characterize the oncologic outcomes 5 years following focal laser ablation (FLA) of localized prostate cancer.

METHODS

36 men underwent in-bore FLA of prostate cancer at our institution between 2013 and 2015. Follow up included digital rectal examination and PSA testing, multiparametric MRI, and MR-guided biopsies. The primary outcome of interest was failure-free survival (FFS), defined as avoidance of salvage whole gland treatment, systemic therapy, metastasis, or death from prostate cancer.

RESULTS

Of the 36 men enrolled, 6 were ultimately lost to follow-up. Of the remaining 30, 25 (83%) have remained free from failure over a median follow-up of 71 months'. Among these patients, 10 (40%) developed in-field recurrence, with 9 undergoing salvage partial gland ablation with FLA, cryotherapy, or high-intensity focused ultrasound. Five patients underwent salvage whole gland or systemic treatment and were thus considered to have failed treatment. Two patients developed metastatic disease, and after receiving radiation and ADT, both currently have undetectable PSA levels. No patients in the cohort died from prostate cancer. Limitations include a small study cohort and lack of standardized surveillance protocols 2 years after treatment.

CONCLUSION

FLA for select cases of prostate cancer provides high rates of FFS, defined as freedom from whole gland or systemic treatment, metastasis, or death from prostate cancer. However, in- or out-of-field recurrence is common and often necessitates salvage ablation.

T2*-weighted MRI as a non-contrast-enhanced method for assessment of focal laser ablation zone extent in prostate cancer thermotherapy

OBJECTIVES

To evaluate utility of T2*-weighted (T2*W) MRI as a tool for intra-operative identification of ablation zone extent during focal laser ablation (FLA) of prostate cancer (PCa), as compared to the current standard of contrast-enhanced T1-weighted (T1W) MRI.

METHODS

Fourteen patients with biopsy-confirmed low- to intermediate-risk localized PCa received MRI-guided (1.5 T) FLA thermotherapy. Following FLA, axial multiple-TE T2*W images, diffusion-weighted images (DWI), and T2-weighted (T2W) images were acquired. Pre- and post-contrast T1W images were also acquired to assess ablation zone (n = 14) extent, as reference standard. Apparent diffusion coefficient (ADC) maps and subtracted contrast-enhanced T1W (sceT1W) images were calculated. Ablation zone regions of interest (ROIs) were outlined manually on all ablated slices. The contrast-to-noise ratio (CBR) of the ablation site ROI relative to the untreated contralateral prostate tissue was calculated on T2*W images and ADC maps and compared to that in sceT1W images.

RESULTS

CBRs in ablation ROIs on T2*W images (TE = 32, 63 ms) did not differ (p = 0.33, 0.25) from those in sceT1W images. Bland-Altman plots of ROI size and CBR in ablation sites showed good agreement between T2*W (TE = 32, 63 ms) and sceT1W images, with ROI sizes on T2*W (TE = 63 ms) strongly correlated (r = 0.64, p = 0.013) and within 15% of those in sceT1W images.

CONCLUSIONS

In detected ablation zone ROI size and CBR, non-contrast-enhanced T2*W MRI is comparable to contrast-enhanced T1W MRI, presenting as a potential method for intra-procedural monitoring of FLA for PCa.

KEY POINTS

• T2*-weighted MR images with long TE visualize post-procedure focal laser ablation zone comparably to the contrast-enhanced T1-weighted MRI. • T2*-weighted MRI could be used as a plausible method for repeated intra-operative monitoring of thermal ablation zone in prostate cancer, avoiding potential toxicity due to heating of contrast agent.

Focal therapy, time to join the multi-disciplinary team discussion?

Organ preserving management is common place in renal cancer, breast cancer and many other solid organ tumours. Current strategies in managing intermediate risk prostate cancer include either whole gland treatment, in the form of radical radiotherapy or radical prostatectomy, or active surveillance. The former is associated with significant post-treatment functional morbidity, whilst the latter associated with the burden of surveillance activity and patient anxiety. Focal therapy would logically fit as a middle ground for suitable patients in whom treatment would be recommended, but where much better functional outcomes may be possible. Ideally this comes without restricting the successful prevention of harm from the cancer. Historically limitations in developing tissue preserving focal therapy strategies in prostate cancer, were due to inaccuracies in tumour characterisation prior to treatment and during follow up. Consequently for example many patients undergoing an active surveillance strategy were being upgraded and upstaged within a short period. Recently high level evidence supporting the use of MRI and targeted biopsies, in particular the PROMIS and PRECISION trials have strengthened clinician confidence in accurate disease characterisation, thus making focal therapy to become a more feasible management option. With improved diagnostic strategies and the publication of reassuring medium term oncological and functional outcomes after focal therapy for intermediate risk prostate cancer, has the time come to require consideration of focal therapy within our multi-disciplinary team (MDT) meetings and with patients? In this review we will consider patient selection and the evidence for the various focal ablation options as well as the surveillance of these patients after treatment. The forthcoming trials to determine comparative effectiveness will be discussed.

Early oncological control following partial gland cryo-ablation: a prospective experience specifying reflex MRI guided biopsy of the ablation zone

BACKGROUND

Several consensus statements recommend serial serum prostate-specific antigen (PSA), multi parametric magnetic resonance imaging (mpMRI), and prostate biopsy following partial gland ablation. We determined the rate of persistent in-field disease following primary partial gland cryo-ablation and whether PSA or mpMRI are reliable predictors of in-field disease persistence.

METHODS

Between March 2017 and July 2019, subjects meeting eligibility criteria for partial gland cryoablation were enrolled into an IRB approved outcomes registry. PSA, mpMRI, and prostate biopsy (four cores targeting the ablation zone + six ipsilateral systematic cores) were performed per protocol 6 months following intervention. Binary logistic regression was employed to calculate odds ratio (OR) of PSA decrease, and suspicious mpMRI effect on cancer persistence. The performance of mpMRI for predicting in-field persistence of PCa was evaluated by area under the receiver operation characteristics curve (AUC).

RESULTS

Of the 83 eligible men undergoing partial gland cryoablation, 70 (84.3%) underwent 6-month protocol prostate biopsy. Five (7.1%) biopsies exhibited any in-field disease persistence. Only one (1.4%) of these cancers was Gleason grade > 1. Neither PSA decrease or suspicious mpMRI reliably predicted cancer persistence, with OR of 1.6 (0.25-8.6) and 1.5 (0.02-1.3), respectively. AUC of mpMRI for predicting in-field disease persistence was 0.554.

CONCLUSIONS

In this cohort of patients undergoing partial gland cryo-ablation, the incidence of persistent disease was low. PSA and mpMRI were not reliable predictors of in-field disease persistence. Based on these data, consideration may be given to deferring early follow-up biopsy in appropriate patients.

Comparative Effectiveness of Radiotherapy versus Focal Laser Ablation in Patients with Low and Intermediate Risk Localized Prostate Cancer

At present, focal laser ablation (FLA) as a new PCa local treatment has attracted attention. We aim at comparing the survival outcomes between radiotherapy (RT) and FLA to reveal whether FLA can be used as an alternative to RT for patients with low and intermediate-risk localized PCa.We conducted analyses with data from the SEER database (2004-2015). Propensity score matching and instrumental variate (IV) were used to reduce the influence of bias and unmeasured confounders maximally.In the adjusted multivariate regression, FLA had lower overall survival (OS) benefits (HR = 1.49; 95%CI: 1.18-1.87; p < 0.001). After propensity score matching, RT still had better OS (HR = 1.50; 95%CI: 1.17-1.93; p = 0.001). The outcomes of IV-adjusted analysis showed FLA was significantly inferior to RT in OS (HR = 1.49; 95%CI: 1.18-1.87). In the subgroup analyses, for those with PSA < 4 ng/mL, FLA showed markedly worse OS and cancer-specific mortality (CSM) outcomes (OS HR = 1.89; 95%CI: 1.01-3.53; p = 0.0466 and CSM HR = 4.25; 95%CI: 1.04-17.43; p = 0.044).FLA is a promising focal therapy of PCa. But our research demonstrated RT still had an obvious advantage in survival benefits over FLA. Using FLA as an alternative treatment for RT requires careful consideration by clinicians.

Targeting the cancer lesion, not the whole prostate

Modern cancer treatment aims to conserve as much healthy tissue as possible. This has been challenging in the treatment of prostate cancer due to the difficulty in imaging the gland and concerns over leaving multifocal cancer untreated. With improvements in imaging and understanding of multifocal prostate cancer evidence now shows accurate treatment of just the primary focus of cancer or the index lesion can control progression or recurrence of the disease. Many different energy sources are now available to target the cancer lesion within the prostate with less significant side-effects on urinary and sexual function compared to radical treatment. Evidence shows that men value these functions highly and would even trade years of life in exchange for preserved retention of continence or erectile function. Focal treatment of prostate cancer aims to provide both cancer control and preservation of sexual and urinary functions so that men do not have to make a choice between the two. This is a treatment option that men clearly want and deserve.

Current state of image-guided focal therapy for prostate cancer

PURPOSE

To review the current evidence regarding protocols and outcomes of image-guided focal therapy (FT) for prostate cancer (PCa).

METHODS

A literature search of the latest published studies assessing primary FT for PCa was carried out in Medline and Cochrane library databases followed by a critical review. FT modalities, follow-up strategies, and oncological and toxicity outcomes were summarized and discussed in this review.

RESULTS

Twenty-four studies with six different sources of energy met the inclusion criteria. A heterogeneity of patient selection, energy sources, treatment templates, and definitions of failure was found among the studies. While a third of patients may be found to have additional cancer burden over 3-5 years following FT, most patients will remain free of a radical procedure. The vast majority of patients maintain urinary continence and good erectile function after FT. Acute urinary retention is the most common complication, whilst severe complications remain rare.

CONCLUSION

An increasing number of prospective studies with longer follow-up have been recently published. Acceptable cancer control and low treatment toxicity after FT have been consistently reported. Follow-up imaging and routine biopsy must be encouraged post-FT. While there is no reliable PSA threshold to predict failure after FT, reporting post-FT positive biopsies and retreatment rates appear to be standard when assessing treatment efficacy.

A tissue-mimicking prostate phantom for 980 nm laser interstitial thermal therapy

Purpose: To develop a phantom with optical and thermal properties matched to human prostate. This phantom will provide a platform for the development and characterization of 980 nm laser interstitial thermal therapy (LITT) systems. Methods: A polyacrylamide gel was doped with Naphthol Green B, Intralipid, and Bovine Serum Albumin (BSA). The necessary concentration of each ingredient was determined by measuring the optical properties via fluence measurements and light diffusion theory. LITT was then performed under the same conditions as a previous clinical trial in which temperature was monitored via a thermal probe. The thermal data and induced coagulation zone were compared to clinical data to illustrate the similarity between the phantom and patient. LITT was also performed under magnetic resonance thermometry (MRT). Results: The requisite concentrations of Naphthol Green B, Intralipid and BSA were found to be 0.144% (w/v), 8.06% (v/v) and 31.4% (v/v) respectively. In the native state, the absorption coefficient and reduced scattering coefficient ( μs' ) were found to be 0.66 ± 0.06 cm^-1 and 8.27 ± 0.50 cm^-1 respectively, with μs' increasing to 17.63 ± 1.41 cm^-1 after coagulation. The thermal response of the phantom was similar to that observed clinically with maximum thermal probe measurements of 64.2 °C and 66.9 °C respectively. The shape of the induced coagulation zone was qualitatively and quantitatively similar to the MRT zone of elevated temperature and the coagulation zone observed clinically. Conclusions: A phantom which simulates optical and thermal response to 980 nm LITT was constructed and demonstrated to be similar to human prostate.

Focal therapy for localized prostate cancer in the era of routine multi-parametric MRI

BACKGROUND

Prostate cancer focal therapy aims to minimize the side-effects of whole gland treatments, such as radical prostatectomy and radiotherapy without compromising oncological efficacy. However, concerns exist regarding the multifocal nature of prostate cancer and the lack of long-term oncological data for this form of treatment. In recent years, the routine adoption of multi-parametric magnetic resonance imaging (mpMRI) of the prostate has improved our ability to select candidates for focal therapy and to accurately deliver this form of prostate cancer treatment.

METHODS

We performed a review of the literature to provide a summary of the oncological and functional outcomes of men receiving primary prostate focal therapy. Furthermore, we discuss the impact of the routine implementation of mpMRI as part of the initial prostate cancer diagnostic pathway on the selection of candidates and delivery of focal therapy. Finally, we summarize knowledge gaps in the field and highlight active clinical trials in this arena.

RESULTS

Primary focal therapy involves the application of one of a number of energies that ablate tissue, such as cryotherapy and high intensity focused ultrasound (HIFU). Success is principally dependent on highly accurate patient selection and disease localization underpinned in large part by the routine integration of pre-biopsy mpMRI. Prospective medium-term follow-up data for primary HIFU and cryotherapy for men with intermediate-risk disease have shown acceptable cancer control with low risk of side effects and complications. Additional research is needed to clearly define an appropriate follow-up approach and to guide the management of in- and out-of-field recurrences. Multiple comparative trials with randomization against standard care are currently underway in men with intermediate- and high-risk prostate cancer.

CONCLUSION

The widespread adoption of prostate mpMRI has led to improved disease localization, enabling the performance of focal therapy as a viable treatment strategy for men with low volume intermediate-risk prostate cancer.

Gold nanoshell-localized photothermal ablation of prostate tumors in a clinical pilot device study

Biocompatible gold nanoparticles designed to absorb light at wavelengths of high tissue transparency have been of particular interest for biomedical applications. The ability of such nanoparticles to convert absorbed near-infrared light to heat and induce highly localized hyperthermia has been shown to be highly effective for photothermal cancer therapy, resulting in cell death and tumor remission in a multitude of preclinical animal models. Here we report the initial results of a clinical trial in which laser-excited gold-silica nanoshells (GSNs) were used in combination with magnetic resonance-ultrasound fusion imaging to focally ablate low-intermediate-grade tumors within the prostate. The overall goal is to provide highly localized regional control of prostate cancer that also results in greatly reduced patient morbidity and improved functional outcomes. This pilot device study reports feasibility and safety data from 16 cases of patients diagnosed with low- or intermediate-risk localized prostate cancer. After GSN infusion and high-precision laser ablation, patients underwent multiparametric MRI of the prostate at 48 to 72 h, followed by postprocedure mpMRI/ultrasound targeted fusion biopsies at 3 and 12 mo, as well as a standard 12-core systematic biopsy at 12 mo. GSN-mediated focal laser ablation was successfully achieved in 94% (15/16) of patients, with no significant difference in International Prostate Symptom Score or Sexual Health Inventory for Men observed after treatment. This treatment protocol appears to be feasible and safe in men with low- or intermediate-risk localized prostate cancer without serious complications or deleterious changes in genitourinary function.

Focal Laser Ablation Versus Radical Prostatectomy for Localized Prostate Cancer: Survival Outcomes From a Matched Cohort

BACKGROUND

Focal therapy for localized prostate cancer (PCa) remains investigational. We aimed to investigate the oncologic outcomes of focal laser ablation (FLA) and compare them with those of radical prostatectomy (RP).

PATIENTS AND METHODS

Patients treated with FLA or RP for localized PCa between 2004 and 2015 were identified from the Surveillance, Epidemiology, and End Results database. Kaplan-Meier curves and multivariate Cox proportional hazard models were utilized to calculate the survival benefits. Propensity score (PS) matching and adjusted standardized mortality ratio weighting (SMRW) models were used to balance the 2 groups. Subgroup analyses according to tumor stage, prostate-specific antigen level, and Gleason score were also conducted.

RESULTS

A total of 12,875 patients were included, of whom 12,433 were treated with RP, whereas 442 were treated with FLA; 321 pairs of patients were eventually matched. Baseline characteristics were well-balanced by PS matching. The mean follow-up was 59.62 months for the RP group and 62.26 months for the FLA group. Before matching, the FLA group had lower but statistically insignificant cancer-specific mortality (CSM) (hazard ratio [HR], 0.61; 95% confidence interval [CI], 0.15-2.45; P = .4879) and higher any-cause mortality (ACM) (HR, 2.35; 95% CI, 1.38-3.98; P = .0016) compared with the RP group, which was supported by the outcomes in the PS-matched cohort (CSM: HR, 0.82; 95% CI, 0.18-3.67; P = .7936; ACM: HR, 2.35; 95% CI, 1.38-3.98; P = .0016) and the SMRW model (CSM: HR, 0.61; 95% CI, 0.15-2.44; P = .4877; ACM: HR, 2.01; 95% CI, 1.18-3.42; P = .0103).

CONCLUSION

Our study suggests that FLA had a higher risk of ACM but an insignificantly lower risk of CSM compared with RP. More high-quality trials are needed to confirm and expand our findings.

Novel focal therapy treatment options for prostate cancer

PURPOSE OF REVIEW

Examine and discuss novel focal therapy treatment options for prostate cancer.

RECENT FINDINGS

With the widespread adoption of mpMRI-guided biopsies for prostate cancer, use of image-guided treatment of prostate cancer has increased. Focal therapies leading to partial gland ablation such as partial prostatectomy, focal laser ablation, irreversible electroporation, vascular targeted photodynamic therapy, and focal radiofrequency ablation have emerged and begun to be properly evaluated. This review covers published phase 1 and 2 trials of each treatment and discusses potential limitations of each modality.

SUMMARY

Focal therapy of prostate cancer is being actively investigated. On the basis of limited published data, the treatments appear to be well tolerated and have an acceptable side effect profile. Importantly, short-term oncologic control has been mixed and there are no long-term outcomes. The acquisition of more data is essential to evaluate these novel technology platforms.

Utility of Multiparametric MRI for Predicting Residual Clinically Significant Prostate Cancer After Focal Laser Ablation

OBJECTIVE. The purpose of this study was to compare in a multireader manner the diagnostic accuracies of 3-T multiparametric MRI interpretation and serial prostate-specific antigen (PSA) measurement in predicting the presence of residual clinically significant prostate cancer after focal laser ablation. MATERIALS AND METHODS. Eighteen men had undergone focal laser ablation for low- or intermediate-risk prostate cancer as part of two National Cancer Institute-funded phase 1 clinical trials. Multiparametric MRI was performed immediately after and 6 and 12 months after focal laser ablation. Serial PSA measurements after focal laser ablation were recorded, and MRI-ultrasound fusion biopsy was performed 6 and 12 months after ablation and served as the reference standard. Multiparametric MRI was performed at 3 T with pelvic phased-array coils. T2-weighted, DW, and dynamic contrast-enhanced MR images were retrospectively assessed by two blinded radiologists using a 3-point Likert scale (0-2). Inter-reader agreement was assessed with the Cohen kappa statistic. The diagnostic accuracies of multiparametric MRI and PSA measurement were compared. RESULTS. Residual clinically significant prostate cancer was identified in 11 of 18 (61%) men. Logistic regression analysis of serial PSA measurements yielded a correct classification rate of 61.1% (p > 0.05). Using a multiparametric MRI threshold score of 4 or greater, both radiologists made correct classifications for 16 of 18 men (89%) at 6 months and 15 of 17 men (88%) at 12 months. Interreader agreement was substantial to excellent for T2-weighted imaging, DWI, and dynamic contrast-enhanced MRI and improved uniformly from 6 to 12 months. Logistic regression analysis of the retrospectively reviewed multiparametric MR images yielded AUCs greater than 0.90 for each radiologist 6 and 12 months after focal laser ablation (p < 0.001). CONCLUSION. Multiparametric MRI 6 and 12 months after focal laser ablation significantly outperformed serial PSA measurements for predicting the presence of residual clinically significant prostate cancer.

Focal laser ablation as clinical treatment of prostate cancer: report from a Delphi consensus project

PURPOSE

To define the role of focal laser ablation (FLA) as clinical treatment of prostate cancer (PCa) using the Delphi consensus method.

METHODS

A panel of international experts in the field of focal therapy (FT) in PCa conducted a collaborative consensus project using the Delphi method. Experts were invited to online questionnaires focusing on patient selection and treatment of PCa with FLA during four subsequent rounds. After each round, outcomes were displayed, and questionnaires were modified based on the comments provided by panelists. Results were finalized and discussed during face-to-face meetings.

RESULTS

Thirty-seven experts agreed to participate, and consensus was achieved on 39/43 topics. Clinically significant PCa (csPCa) was defined as any volume Grade Group 2 [Gleason score (GS) 3+4]. Focal therapy was specified as treatment of all csPCa and can be considered primary treatment as an alternative to radical treatment in carefully selected patients. In patients with intermediate-risk PCa (GS 3+4) as well as patients with MRI-visible and biopsy-confirmed local recurrence, FLA is optimal for targeted ablation of a specific magnetic resonance imaging (MRI)-visible focus. However, FLA should not be applied to candidates for active surveillance and close follow-up is required. Suitability for FLA is based on tumor volume, location to vital structures, GS, MRI-visibility, and biopsy confirmation.

CONCLUSION

Focal laser ablation is a promising technique for treatment of clinically localized PCa and should ideally be performed within approved clinical trials. So far, only few studies have reported on FLA and further validation with longer follow-up is mandatory before widespread clinical implementation is justified.

Focal therapy for localized prostate cancer: is there a "middle ground" between active surveillance and definitive treatment?

In recent years, it has come a long way in the diagnosis, treatment, and follow-up of prostate cancer. Beside this, it was argued that definitive treatments could cause overtreatment, particularly in the very low, low, and favorable risk group. When alternative treatment and follow-up methods are being considered for this group of patients, active surveillance is seen as a good alternative for patients with very low and low-risk groups in this era. However, it has become necessary to find other alternatives for patients in the favorable risk group or patients who cannot adopt active follow-up. In the light of technological developments, the concept of focal therapy was introduced with the intensification of research to treat only the lesioned area instead of treating the entire organ for prostate lesions though there are not many publications about many of them yet. According to the initial results, it was understood that the results could be good if the appropriate focal therapy technique was applied to the appropriate patient. Thus, focal therapies have begun to find their "middle ground" place between definitive therapies and active follow-up.

Ablation energies for focal treatment of prostate cancer

Context

In recent years, focal therapy has emerged as a treatment option for a selected group of men with localized prostate cancer. Cryotherapy and high-intensity focused ultrasound (HIFU) are the most investigated types of focal treatment with other options currently under evaluation.

Objective

The objective of the study was to give a comprehensive overview of six available focal treatment options for prostate cancer with their rationale, delivery mechanism, and outcomes.

Information acquisition

The SIU ICUD chapter on available Energies to Treat Prostate Cancer was used as a guide to describe the different technologies. For outcomes, a literature search was conducted using PubMed key words including focal therapy, HIFU, cryotherapy, irreversible electroporation, vascular-targeted photodynamic therapy, laser interstitial therapy, radiofrequency ablation, microwave therapy, and their synonyms in MeSH terms.

Conclusion

Focal therapy appears to have encouraging outcomes on quality of life and urinary and erectile function. For oncological outcomes, it is challenging to fully interpret the outcomes due to heterogeneity in patient selection and short-term follow-up.

Electronic supplementary material

The online version of this article (10.1007/s00345-018-2364-x) contains supplementary material, which is available to authorized users.

Twelve-month prostate volume reduction after MRI-guided transurethral ultrasound ablation of the prostate

PURPOSE

To quantitatively assess 12-month prostate volume (PV) reduction based on T2-weighted MRI and immediate post-treatment contrast-enhanced MRI non-perfused volume (NPV), and to compare measurements with predictions of acute and delayed ablation volumes based on MR-thermometry (MR-t), in a central radiology review of the Phase I clinical trial of MRI-guided transurethral ultrasound ablation (TULSA) in patients with localized prostate cancer.

MATERIALS AND METHODS

Treatment day MRI and 12-month follow-up MRI and biopsy were available for central radiology review in 29 of 30 patients from the published institutional review board-approved, prospective, multi-centre, single-arm Phase I clinical trial of TULSA. Viable PV at 12 months was measured as the remaining PV on T2-weighted MRI, less 12-month NPV, scaled by the fraction of fibrosis in 12-month biopsy cores. Reduction of viable PV was compared to predictions based on the fraction of the prostate covered by the MR-t derived acute thermal ablation volume (ATAV, 55°C isotherm), delayed thermal ablation volume (DTAV, 240 cumulative equivalent minutes at 43°C thermal dose isocontour) and treatment-day NPV. We also report linear and volumetric comparisons between metrics.

RESULTS

After TULSA, the median 12-month reduction in viable PV was 88%. DTAV predicted a reduction of 90%. Treatment day NPV predicted only 53% volume reduction, and underestimated ATAV and DTAV by 36% and 51%.

CONCLUSION

Quantitative volumetry of the TULSA phase I MR and biopsy data identifies DTAV (240 CEM43 thermal dose boundary) as a useful predictor of viable prostate tissue reduction at 12 months. Immediate post-treatment NPV underestimates tissue ablation.

KEY POINTS

• MRI-guided transurethral ultrasound ablation (TULSA) achieved an 88% reduction of viable prostate tissue volume at 12 months, in excellent agreement with expectation from thermal dose calculations. • Non-perfused volume on immediate post-treatment contrast-enhanced MRI represents only 64% of the acute thermal ablation volume (ATAV), and reports only 60% (53% instead of 88% achieved) of the reduction in viable prostate tissue volume at 12 months. • MR-thermometry-based predictions of 12-month prostate volume reduction based on 240 cumulative equivalent minute thermal dose volume are in excellent agreement with reduction in viable prostate tissue volume measured on pre- and 12-month post-treatment T2w-MRI.

Two-year Outcomes Following Focal Laser Ablation of Localized Prostate Cancer

BACKGROUND

There is no consensus regarding how to assess oncological control following focal ablation of prostate cancer.

OBJECTIVE

To assess quality of life and in-field recurrence following focal laser ablation (FLA).

DESIGN, SETTING, AND PARTICIPANTS

Of 34 men participating in a prospective outcomes study following FLA, 32 underwent prostate-specific antigen (PSA) testing and magnetic resonance imaging (MRI) at 6 mo and 2 yr. All underwent assessment of urinary and sexual function at 1 yr.

INTERVENTION

FLA and MRI-targeted biopsy of the ablation zone.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The American Urological Association Symptom Score and the Sexual Health Inventory for Men at baseline and 12 mo were compared using a two-sided Wilcoxon signed-rank test with a significance level of p=0.05. The percentage of positive and negative in-field biopsies was calculated for suspicious and nonsuspicious post-ablation MRI scans.

RESULTS AND LIMITATIONS

FLA was associated with no adverse impact on urinary or sexual function. For men with suspicious MRI (MRI+) findings, in-field disease recurrence of intermediate and low risk disease was detected in 75% and 25% of cases, respectively. For men with nonsuspicious MRI (MRI-) findings, in-field disease recurrence of intermediate- and low-risk disease was detected in 22.4% and 50% of cases, respectively. The change in PSA from baseline did not discriminate cases with MRI- findings with and without cancer at 2 yr.

CONCLUSIONS

MRI reliably identifies in-field recurrence of only intermediate-risk prostate cancer at 2 yr after FLA. A biopsy of the ablation zone must be performed for MRI+ findings. The decision to perform an ablation-zone biopsy for men with MRI- scans should be influenced by whether detection of low-risk disease would influence management.

PATIENT SUMMARY

Our study provides compelling evidence that men should undergo interval magnetic resonance imaging to assess the probability of intermediate-risk disease in the ablation zone following focal laser ablation of localized prostate cancer.

Which technology to select for primary focal treatment of prostate cancer?-European Section of Urotechnology (ESUT) position statement

BACKGROUND

With growing interest in focal therapy (FT) of prostate cancer (PCa) there is an increasing armamentarium of treatment modalities including high-intensity focused ultrasound (HIFU), cryotherapy, focal laser ablation (FLA), irreversible electroporation (IRE), vascular targeted photodynamic therapy (VTP), focal brachytherapy (FBT) and stereotactic ablative radiotherapy (SABR). Currently there are no clear recommendations as to which of these technologies are appropriate for individual patient characteristics. Our intention was to review the literature for special aspects of the different technologies that might be of advantage depending on individual patient and tumour characteristics.

METHODS

The current literature on FT was screened for the following factors: morbidity, repeatability, tumour risk category, tumour location, tumour size and prostate volume and anatomical issues. The ESUT expert panel arrived at consensus regarding a position statement on a structured pathway for available FT technologies based on a combination of the literature and expert opinion.

RESULTS

Side effects were low across different studies and FT modalities with urinary continence rates of 90-100% and erectile dysfunction between 5 and 52%. Short to medium cancer control based on post-treatment biopsies were variable between ablative modalities. Expert consensus suggested that posterior lesions are better amenable to FT using HIFU. Cryotherapy provides best possible outcomes for anterior tumours. Apical lesions, when treated with FBT, may yield the least urethral morbidity.

CONCLUSIONS

Further prospective trials are required to assess medium to long term disease control of different ablative modalities for FT. Amongst different available FT modalities our ESUT expert consensus suggests that some may be better for diffe`rent tumour locations. Tumour risk, tumour size, tumour location, and prostate volume are all important factors to consider and might aid in designing future FT trials.

MR-guided biopsy and focal therapy: new options for prostate cancer management

PURPOSE OF REVIEW

Options for prostate cancer management are rapidly expanding. The recent advent of MRI technology has led to guided prostate biopsies by radiologists working in-bore or by urologists using MR/US fusion technology. The resulting tumor visualization now provides the option of focal therapy. Currently available are highly directed energies - focused ultrasound (HIFU), cryotherapy, and laser - all offering the hope of curing prostate cancer with few side effects.

RECENT FINDINGS

MRI now enables visualization of many prostate cancers. MR/US fusion biopsy makes possible the targeted biopsy of suspicious lesions efficiently in the urology clinic. Several fusion devices are now commercially available. Focal therapy, a derivative of targeted biopsy, is reshaping the approach to treatment of some prostate cancers. Focal laser ablation, originally done in the MRI gantry (in-bore), promises to soon become feasible in a clinic setting (out-of-bore) under local anesthesia. Other focal therapy options, including HIFU and cryotherapy, are currently available. Herein are summarized outcomes data on focal therapy modalities.

SUMMARY

MRI-guided biopsy is optimizing prostate cancer diagnosis. Focal therapy, an outgrowth of guided biopsy, promises to become a well tolerated and effective approach to treating many men with prostate cancer while minimizing the risks of incontinence and impotence from radical treatment.

Focal Therapy in Primary Localised Prostate Cancer: The European Association of Urology Position in 2018

Radical treatment of localised prostate cancer is recognised to be an unnecessary intervention or overtreatment in many men. Consequently, there has been a rapid uptake in the use of focal ablative therapies. However, there are several biological and practical concerns about such approaches as they have yet to be proved as robust treatment options. In particular, the multifocal nature of prostate cancer argues against unifocal treatment, while limitations in imaging can preclude the accurate identification of the number, location, and extent of prostate cancer foci. To date, a number of ablative options have reported results on mainly low-risk disease. Most series are relatively immature, with a lack of consistent follow-up, and the morbidity of retreatment is often not considered. The authors consider focal therapy to be an investigational modality, and encourage prospective recording of outcomes and recruitment of suitable patients.

PATIENT SUMMARY

Focal therapy of prostate cancer is the targeted destruction of cancer within a specific part of the prostate gland, sparing the rest of the prostate and nearby tissue. This procedure could potentially reduce side effects when compared with established standard treatments, such as surgery or radiotherapy, which treat the entire prostate. Studies show that for most men with low-risk cancer, active surveillance is the preferred treatment option. However, the available data regarding all forms of focal therapy are still poor and inconclusive. Consequently, due to both the lack of clear results associated with focal therapy and the difficulties in detecting all cancerous areas of the prostate, focal therapy should be considered an investigational modality only.

Focal Ablation of Prostate Cancer

The challenge to the urology community is to reduce the risks of screening and treatment by reducing the number of men undergoing unnecessary biopsy and whole-gland curative treatment of low-risk disease. There is compelling evidence that focal ablation of prostate cancer is truly minimally invasive and offers major functional advantages over whole-gland treatment.

A comparison of time taken to return to baseline erectile function following focal and whole gland ablative therapies for localized prostate cancer: A systematic review

OBJECTIVES

To systematically review erectile function (EF) outcomes following primary whole gland (WG) and focal ablative therapies for localized prostate cancer to ascertain whether the treatment modality or intended treatment volume affects the time taken to recover baseline EF.

METHOD AND MATERIALS

A systematic review was performed according to the preferred reporting items for systematic review and meta-analysis statement. Inclusion criteria were men with localized prostate cancer treated with primary, ablative therapy. Primary outcome was the return to baseline EF measured with objective, validated symptoms scores. Secondary outcome was use of phosphodiesterase inhibitors or erectile aids. Meta-analysis was not performed owing to heterogenous outcome measures.

RESULTS

Of 222 articles identified in February 2017, 55 studies which reported EF after ablative therapy were identified but only 17 used validated outcome measures and met inclusion criteria. WG cryotherapy was used in 2 studies, WG high-intensity focused ultrasound (HIFU) in 5, focal cryotherapy in 2, focal HIFU in 3, focal phototherapy or laser therapy in 4, vascular-targeted photodynamic therapy in 3, and irreversible electroporation in 2. WG cryotherapy was associated with a significant decline in EF at 6 months with minimal improvement at 36 months. Baseline IIEF-15 of patients undergoing focal HIFU fell 30 points at 1 month but returned to baseline by 6 months. The remaining focal therapies demonstrated minimal or no effect on EF, but the men in these studies had small foci of disease. The review is limited by lack of randomized studies and heterogenous outcome measures.

CONCLUSIONS

Most studies assessing the outcomes of focal therapy on sexual function were not of high quality, used heterogenous outcomes, and had relatively short follow up, highlighting the need for more robustly designed studies using validated patient reported outcome measures  for comparison. However, FT in general resulted in less effect on EF than WG ablation.

MR Imaging-Guided Focal Treatment of Prostate Cancer: An Update

Focal treatment of prostate cancer has evolved from a concept to a practice in the recent few years and is projected to fill an existing need, bridging the gap between conservative and radical traditional treatment options. With its low morbidity and rapid recovery time compared with whole-gland treatment alternatives, focal therapy is poised to gain more acceptance among patients and health care providers. As our experience with focal treatment matures and evidence continues to accrue, the landscape of this practice might look quite different in the future.

[Evaluation and results of ablative therapies in prostate cancer]

OBJECTIVE

To perform a state of the art about methods of evaluation and present results in ablative therapies for localized prostate cancer.

METHODS

A review of the scientific literature was performed in Medline database (http://www.ncbi.nlm.nih.gov) and Embase (http://www.embase.com) using different associations of keywords. Publications obtained were selected based on methodology, language and relevance. After selection, 102 articles were analysed.

RESULTS

Analyse the results of ablative therapies is presently difficult considering the heterogeneity of indications, techniques and follow-up. However, results from the most recent and homogeneous studies are encouraging. Oncologically, postoperative biopsies (the most important criteria) are negative (without any tumor cells in the treated area) in 75 to 95%. Functionally, urinary and sexual pre-operative status is spared (or recovered early) in more than 90% of the patients treated. More and more studies underline also the correlation between the results and the technique used considering the volume of the gland and, moreover, the "index lesion" localization.

CONCLUSION

The post-treatment pathological evaluation by biopsies (targeted with MRI or, perhaps in a near future, with innovative ultrasonography) is the corner stone of oncological evaluation of ablative therapies. Ongoing trials will allow to standardize the follow-up and determine the best indication and the best techniques in order to optimize oncological and functional results for each patient treated.

Multimodal Imaging in Focal Therapy Planning and Assessment in Primary Prostate Cancer

PURPOSE

There is increasing interest in focal therapy (male lumpectomy) of localized low-intermediate risk prostate cancer. Focal therapy is typically associated with low morbidity and provides the possibility of retreatment. Imaging is pivotal in stratification of men with localized prostate cancer for active surveillance, focal therapy or radical intervention. This article provides a concise review of focal therapy and the evolving role of imaging in this clinical setting.

METHODS

We performed a narrative and critical literature review by searching PubMed/Medline database from January 1997 to January 2017 for articles in the English language and the use of search keywords "focal therapy", "prostate cancer", and "imaging".

RESULTS

Most imaging studies are based on multiparametric magnetic resonance imaging. Transrectal ultrasound is inadequate independently but multiparametric ultrasound may provide new prospects. Positron emission tomography with radiotracers targeted to various underlying tumor biological features may provide unprecedented new opportunities. Multimodal Imaging appears most useful in localization of intraprostatic dominant index lesions amenable to focal therapy, in early assessment of therapeutic efficacy and potential need for additional focal treatments or transition to whole-gland therapy, and in predicting short-term and long-term outcomes.

CONCLUSION

Multimodal imaging is anticipated to play an increasing role in the focal therapy planning and assessment of low-intermediate risk prostate cancer and thereby moving this form of treatment option forward in the clinic.

Multi-parametric MRI imaging of the prostate-implications for focal therapy

The primary goal of a focal therapy treatment paradigm is to achieve cancer control through targeted tissue destruction while simultaneously limiting deleterious effects on peri-prostatic structures. Focal therapy approaches are employed in several oncologic treatment protocols, and have been shown to provide equivalent cancer control for malignancies such as breast cancer and renal cell carcinoma. Efforts to develop a focal therapy approach for prostate cancer have been challenged by several concepts including the multifocal nature of the disease and limited capability of prostate ultrasound and systematic biopsy to reliably localize the site(s) and aggressiveness of disease. Multi-parametric MRI (mpMRI) of the prostate has significantly improved disease localization, spatial demarcation and risk stratification of cancer detected within the prostate. The accuracy of this imaging modality has further enabled the urologist to improve biopsy approaches using targeted biopsy via MRI-ultrasound fusion. From this foundation, an improved delineation of the location of disease has become possible, providing a critical foundation to the development of a focal therapy strategy. This chapter reviews the accuracy of mpMRI for detection of “aggressive“ disease, the accuracy of mpMRI in determining the tumor volume, and the ability of mpMRI to accurately identify the index lesion. While mpMRI provides a critical, first step in developing a strategy for focal therapy, considerable questions remain regarding the relationship between MR identified tumor volume and pathologic tumor volume, the accuracy and utility of mpMRI for treatment surveillance and the optimal role and timing of follow-up mpMRI.

Natural Orifice Transluminal Endoscopic Partial Prostatectomy: A Real-time Image-guided Focal Extirpative Feasibility Study

OBJECTIVE

To assess the feasibility of focal endoscopic excision of prostate cancer (PCa) under guidance of real-time magnetic resonance imaging (MRI) or magnetic ultrasound fusion (MUF).

MATERIALS AND METHODS

Using a cadaveric model, multifocal PCa was simulated using 2 MRI-compatible fiducial markers. These were inserted transrectally and used to generate regions of interests (ROIs) on a 1.5-T surface-coil MRI. The first marker was placed in the right mid-peripheral zone (ROI 1), and the second marker was placed in the left seminal vesicle as a referent lesion for subsequent imaging. MRI of the specimen was then obtained. The radiologist created ROIs using fusion biopsy system at each marker. Two additional incidental ROIs were identified in the left transitional zone (ROI 2-suspicious for benign prostatic hyperplasia nodule) and in the right anterior peripheral zone (ROI 3-suspicious for PCa). Holmium laser enucleation of the transitional zone of the prostate was performed to gain access to the peripheral zone lesions. MUF was used during endoscopic laser excision to convey targeting accuracy. The cadaver was then reimaged to determine the adequacy of resection and examined for histopathologic correlation.

RESULTS

Real-time MUF imaging identified the target lesions consistently at the locations designated as ROIs. Complete endoscopic resection of ROIs was possible. Repeated MUF imaging and the postprocedure MRI confirmed the completeness of resection. Pathologic examination demonstrated complete excision, intact neurovascular bundles, and posterior prostatic capsule.

CONCLUSION

This approach may represent a new minimally invasive frontier for focal surgical resection of PCa, making histopathologic margin status determination possible.

Focal Laser Ablation of Prostate Cancer: Feasibility of Magnetic Resonance Imaging-Ultrasound Fusion for Guidance

PURPOSE

Focal laser ablation is a potential treatment in some men with prostate cancer. Currently focal laser ablation is performed by radiologists in a magnetic resonance imaging unit (in bore). We evaluated the safety and feasibility of performing focal laser ablation in a urology clinic (out of bore) using magnetic resonance imaging-ultrasound fusion for guidance.

MATERIALS AND METHODS

A total of 11 men with intermediate risk prostate cancer were enrolled in this prospective, institutional review board approved pilot study. Magnetic resonance imaging-ultrasound fusion was used to guide laser fibers transrectally into regions of interest harboring intermediate risk prostate cancer. Thermal probes were inserted for real-time monitoring of intraprostatic temperatures during laser activation. Multiparametric magnetic resonance imaging (3 Tesla) was done immediately after treatment and at 6 months along with comprehensive fusion biopsy.

RESULTS

Ten of 11 patients were successfully treated while under local anesthesia. Mean procedure time was 95 minutes (range 71 to 105). Posttreatment magnetic resonance imaging revealed a confined zone of nonperfusion in all 10 men. Mean zone volume was 4.3 cc (range 2.1 to 6.0). No CTCAE grade 3 or greater adverse events developed and no changes were observed in urinary or sexual function. At 6 months magnetic resonance imaging-ultrasound fusion biopsy of the treatment site showed no cancer in 3 patients, microfocal Gleason 3 + 3 in another 3 and persistent intermediate risk prostate cancer in 4.

CONCLUSIONS

Focal laser ablation of prostate cancer appears safe and feasible with the patient under local anesthesia in a urology clinic using magnetic resonance imaging-ultrasound fusion for guidance and thermal probes for monitoring. Further development is necessary to refine out of bore focal laser ablation and additional studies are needed to determine appropriate treatment margins and oncologic efficacy.