Evaluation of Outcomes Following Focal Ablative Therapy for Treatment of Localized Clinically Significant Prostate Cancer in Patients >70 Years: A Multi-institute, Multi-energy 15-Year Experience.

PURPOSE: In older patients who do not wish to undergo watchful waiting, focal therapy could be an alternative to the more morbid radical treatment. We evaluated the role of focal therapy in patients 70 years and older as an alternative management modality. MATERIALS AND METHODS: A total of 649 patients across 11 UK sites receiving focal high-intensity focused ultrasound or cryotherapy between June 2006 and July 2020 reported within the UK-based HEAT (HIFU Evaluation and Assessment of Treatment) and ICE (International Cryotherapy Evaluation) registries were evaluated. Primary outcome was failure-free survival, defined by need for more than 1 focal reablation, progression to radical treatment, development of metastases, need for systemic treatment, or prostate cancer-specific death. This was compared to the failure-free survival in patients undergoing radical treatment via a propensity score weighted analysis. RESULTS: Median age was 74 years (IQR: 72, 77) and median follow-up 24 months (IQR: 12, 41). Sixty percent had intermediate-risk disease and 35% high-risk disease. A total of 113 patients (17%) required further treatment. Sixteen had radical treatment and 44 required systemic treatment. Failure-free survival was 82% (95% CI: 76%-87%) at 5 years. Comparing patients who had radical therapy to those who had focal therapy, 5-year failure-free survival was 96% (95% CI: 93%-100%) and 82% (95% CI: 75%-91%) respectively (P < .001). Ninety-three percent of those in the radical treatment arm had received radiotherapy as their primary treatment with its associated use of androgen deprivation therapy, thereby leading to potential overestimation of treatment success in the radical treatment arm, especially given the similar metastases-free and overall survival rates seen. CONCLUSIONS: We propose focal therapy to be an effective management option for the older or comorbid patient who is unsuitable for or not willing to undergo radical treatment.

External validation of a risk model predicting failure of salvage focal ablation for prostate cancer.

OBJECTIVES: To externally validate a published model predicting failure within 2 years after salvage focal ablation in men with localised radiorecurrent prostate cancer using a prospective, UK multicentre dataset. PATIENTS AND METHODS: Patients with biopsy-confirmed ≤T3bN0M0 cancer after previous external beam radiotherapy or brachytherapy were included from the FOcal RECurrent Assessment and Salvage Treatment (FORECAST) trial (NCT01883128; 2014-2018; six centres), and from the high-intensity focussed ultrasound (HIFU) Evaluation and Assessment of Treatment (HEAT) and International Cryotherapy Evaluation (ICE) UK-based registries (2006-2022; nine centres). Eligible patients underwent either salvage focal HIFU or cryotherapy, with the choice based predominantly on anatomical factors. Per the original multivariable Cox regression model, the predicted outcome was a composite failure outcome. Model performance was assessed at 2 years post-salvage with discrimination (concordance index [C-index]), calibration (calibration curve and slope), and decision curve analysis. For the latter, two clinically-reasonable risk threshold ranges of 0.14-0.52 and 0.26-0.36 were considered, corresponding to previously published pooled 2-year recurrence-free survival rates for salvage local treatments. RESULTS: A total of 168 patients were included, of whom 84/168 (50%) experienced the primary outcome in all follow-ups, and 72/168 (43%) within 2 years. The C-index was 0.65 (95% confidence interval 0.58-0.71). On graphical inspection, there was close agreement between predicted and observed failure. The calibration slope was 1.01. In decision curve analysis, there was incremental net benefit vs a 'treat all' strategy at risk thresholds of ≥0.23. The net benefit was therefore higher across the majority of the 0.14-0.52 risk threshold range, and all of the 0.26-0.36 range. CONCLUSION: In external validation using prospective, multicentre data, this model demonstrated modest discrimination but good calibration and clinical utility for predicting failure of salvage focal ablation within 2 years. This model could be reasonably used to improve selection of appropriate treatment candidates for salvage focal ablation, and its use should be considered when discussing salvage options with patients. Further validation in larger, international cohorts with longer follow-up is recommended.

Prostate Radiofrequency Focal Ablation (ProRAFT) Trial: A Prospective Development Study Evaluating a Bipolar Radiofrequency Device to Treat Prostate Cancer.

PURPOSE: We determined the early efficacy of bipolar radiofrequency ablation with a coil design for focal ablation of clinically significant localized prostate cancer visible at multiparametric magnetic resonance imaging. MATERIALS AND METHODS: A prospective IDEAL phase 2 development study (Focal Prostate Radiofrequency Ablation, NCT02294903) recruited treatment-naïve patients with a single focus of significant localized prostate cancer (Gleason 7 or 4 mm or more of Gleason 6) concordant with a lesion visible on multiparametric magnetic resonance imaging. Intervention was a focal ablation with a bipolar radiofrequency system (Encage™) encompassing the lesion and a predefined margin using nonrigid magnetic resonance imaging-ultrasound fusion. Primary outcome was the proportion of men with absence of significant localized disease on biopsy at 6 months. Trial followup consisted of serum prostate specific antigen, multiparametric magnetic resonance imaging at 1 week, and 6 and 12 months post-ablation. Validated patient reported outcome measures for urinary, erectile and bowel functions, and adverse events monitoring system were used. Analyses were done on a per-protocol basis. RESULTS: Of 21 patients recruited 20 received the intervention. Baseline characteristics were median age 66 years (IQR 63-69) and preoperative median prostate specific antigen 7.9 ng/ml (5.3-9.6). A total of 18 patients (90%) had Gleason 7 disease with median maximum cancer 7 mm (IQR 5-10), for a median of 2.8 cc multiparametric magnetic resonance imaging lesions (IQR 1.4-4.8). Targeted biopsy of the treated area (median number of cores 6, IQR 5-8) showed absence of significant localized prostate cancer in 16/20 men (80%), concordant with multiparametric magnetic resonance imaging. There was a low profile of side effects at patient reported outcome measures analysis and there were no serious adverse events. CONCLUSIONS: Focal therapy of significant localized prostate cancer associated with a magnetic resonance imaging lesion using bipolar radiofrequency showed early efficacy to ablate cancer with low rates of genitourinary and rectal side effects.

Outcomes of the RAFT trial: robotic surgery after focal therapy.

OBJECTIVES: To report toxicity of treatment observed in men participating in the Robotic surgery After Focal Therapy (RAFT) clinical trial. PATIENTS AND METHODS: Men were eligible for this prospective single group interventional study if they had histologically confirmed recurrent/residual prostate adenocarcinoma following primary FT. The short-form Expanded Prostate Cancer Index Composite (EPIC-26) measured prior to salvage robotic prostatectomy (S-RARP) and 3-monthly post-operatively together with Clavien-Dindo complications (I-IV). Secondary outcomes included biochemical recurrence-free survival (BCFS) following surgery and need for salvage treatment after surgery. This study is registered with ClinicalTrials.gov NCT03011606. RESULTS: Twenty-four men were recruited between February 2016 and September 2018. 1 patient withdrew from the trial after consenting and before S-RARP. 23 men completed 12-month post S-RARP follow-up. Median EPIC-26 urinary continence scores initially deteriorated after 3 months (82.4 vs 100) but there was no statistically significant difference from baseline at 12 months (100 vs 100, P = 0.31). Median lower urinary tract symptom scores improved after 12 months compared to baseline (93.8 vs 87.5, P = 0.01). At 12 months, 19/23 (83%) were pad-free and 22/23 (96%) required 0/1 pads. Median sexual function subscale scores deteriorated and remained low at 12 months (22.2 vs 58.3, P < 0.001). Utilising a minimally important difference of nine points, at 12 months after surgery 17/23 (74%) reported urinary continence to be 'better' or 'not different' to pre-operative baseline. The corresponding figure for sexual function (utilising a minimally important difference of 12 points) was 7/23 (30%). There was no statistically significant difference on median bowel/hormonal subscale scores. Only a single patient had a post-operative complication (Clavien-Dindo Grade I). BCFS at 12 months after surgery was 82.6% (95% confidence interval [CI]: 60.1-93.1%) while 4/23 (17%) received salvage radiation. CONCLUSIONS: The RAFT clinical trial suggests toxicity of surgery after FT is low, with good urinary function outcomes, albeit sexual function deteriorated overall. Oncological outcomes at 12 months appear acceptable.

Natural history of prostate cancer on active surveillance: stratification by MRI using the PRECISE recommendations in a UK cohort.

OBJECTIVES: The PRECISE recommendations for magnetic resonance imaging (MRI) in patients on active surveillance (AS) for prostate cancer (PCa) include repeated measurement of each lesion, and attribution of a PRECISE radiological progression score for the likelihood of clinically significant change over time. We aimed to compare the PRECISE score with clinical progression in patients who are managed using an MRI-led AS protocol. METHODS: A total of 553 patients on AS for low- and intermediate-risk PCa (up to Gleason score 3 + 4) who had two or more MRI scans performed between December 2005 and January 2020 were included. Overall, 2161 scans were retrospectively re-reported by a dedicated radiologist to give a PI-RADS v2 score for each scan and assess the PRECISE score for each follow-up scan. Clinical progression was defined by histological progression to ≥ Gleason score 4 + 3 (Gleason Grade Group 3) and/or initiation of active treatment. Progression-free survival was assessed using Kaplan-Meier curves and log-rank test was used to assess differences between curves. RESULTS: Overall, 165/553 (30%) patients experienced the primary outcome of clinical progression (median follow-up, 74.5 months; interquartile ranges, 53-98). Of all patients, 313/553 (57%) did not show radiological progression on MRI (PRECISE 1-3), of which 296/313 (95%) had also no clinical progression. Of the remaining 240/553 patients (43%) with radiological progression on MRI (PRECISE 4-5), 146/240 (61%) experienced clinical progression (p < 0.0001). Patients with radiological progression on MRI (PRECISE 4-5) showed a trend to an increase in PSA density. CONCLUSIONS: Patients without radiological progression on MRI (PRECISE 1-3) during AS had a very low likelihood of clinical progression and many could avoid routine re-biopsy. KEY POINTS: • Patients without radiological progression on MRI (PRECISE 1-3) during AS had a very low likelihood of clinical progression and many could avoid routine re-biopsy. • Clinical progression was almost always detectable in patients with radiological progression on MRI (PRECISE 4-5) during AS. • Patients with radiological progression on MRI (PRECISE 4-5) during AS showed a trend to an increase in PSA density.

Update on Multiparametric Prostate MRI During Active Surveillance: Current and Future Trends and Role of the PRECISE Recommendations.

Active surveillance for low-to-intermediate risk prostate cancer is a conservative management approach that aims to avoid or delay active treatment until there is evidence of disease progression. In recent years, multiparametric MRI (mpMRI) has been increasingly used in active surveillance and has shown great promise in patient selection and monitoring. This has been corroborated by publication of the Prostate Cancer Radiologic Estimation of Change in Sequential Evaluation (PRECISE) recommendations, which define the ideal reporting standards for mpMRI during active surveillance. The PRECISE recommendations include a system that assigns a score from 1 to 5 (the PRECISE score) for the assessment of radiologic change on serial mpMRI scans. PRECISE scores are defined as follows: a score of 3 indicates radiologic stability, a score of 1 or 2 denotes radiologic regression, and a score of 4 or 5 indicates radiologic progression. In the present study, we discuss current and future trends in the use of mpMRI during active surveillance and illustrate the natural history of prostate cancer on serial scans according to the PRECISE recommendations. We highlight how the ability to classify radiologic change on mpMRI with use of the PRECISE recommendations helps clinical decision making.

Pathological Findings and Magnetic Resonance Imaging Concordance at Salvage Radical Prostatectomy for Local Recurrence following Partial Ablation Using High Intensity Focused Ultrasound.

PURPOSE: We describe the pathological characteristics of recurrence following high intensity focused ultrasound partial ablation in men treated with salvage robot-assisted radical prostatectomy. We assessed the sensitivity of magnetic resonance imaging before salvage robot-assisted radical prostatectomy in these men. MATERIALS AND METHODS: A total of 35 men underwent salvage robot-assisted radical prostatectomy after high intensity focused ultrasound partial ablation from 2012 to 2018. We compared clinicopathological characteristics before ultrasound and before salvage prostatectomy after ultrasound to histopathology on salvage prostatectomy. We assessed infield recurrence, out of field disease, positive surgical margins and magnetic resonance imaging sensitivity before salvage robot-assisted radical prostatectomy. RESULTS: Before high intensity focused ultrasound 55.9% of men had multifocal disease and 47.1% had Gleason 3 + 3 disease outside the treatment field. Median time to salvage prostatectomy was 16 months (IQR 11-26). Indications for salvage prostatectomy were infield recurrence in 55.8% of cases, out of field recurrence in 20.6%, and infield and out of field recurrence in 23.5%. On salvage prostatectomy histopathology revealed significant cancer, defined as ISUP (International Society of Urological Pathology) 2 or greater, infield in 97.1% of cases, out of field in 81.3%, and infield and out of field in 79.4%. Of the cases 82.4% were adversely reclassified at salvage prostatectomy compared to 67.6% before ultrasound. The positive surgical margin rate was 40.0%. Of the positive margins 84.6% were in the region of previous ultrasound despite wide excision, including pT2 in 28.6%, pT3 in 47.6% and size 3 mm or greater, pT3 or multifocal (ie significant) in 31.4%. After ultrasound the sensitivity of magnetic resonance imaging for infield and out of field recurrence was 81.8% and 60.7%, respectively. CONCLUSIONS: Salvage robot-assisted radical prostatectomy may confer a higher risk of positive surgical margins, upgrading and up-staging than primary robot-assisted radical prostatectomy. High intensity focused ultrasound carries a risk of recurrence inside and outside the ablation zone. This information may inform salvage surgical planning and patient counseling regarding the choice of initial therapy and salvage treatment after high intensity focused ultrasound.

Targeted biopsy of the prostate: does this result in improvement in detection of high-grade cancer or the occurrence of the Will Rogers phenomenon?

OBJECTIVE: To investigate whether patients with Gleason 3 + 4 cancer on transrectal biopsy are upgraded after undergoing transperineal magnetic resonance imaging (MRI)-targeted biopsy and whether this has implications for current clinical practice. PATIENTS AND METHODS: In this retrospective analysis we examined 107 consecutive patients presenting at a single tertiary referral centre (July 2012 to July 2016) with prostate cancer of Gleason score 3 + 4 on transrectal ultrasonography (TRUS)-guided systematic non-targeted biopsy who then underwent a multiparametric MRI followed by MRI-targeted transperineal prostate biopsy for accurate risk stratification and localization. RESULTS: The patients' mean (sd) age was 67.0 (8.0) years, and they had a median (interquartile range) PSA concentration of 6.2 (4.7-9.6) ng/mL. Of the 107 patients, 84 (78.5%) had Gleason 3 + 4 on both transrectal systematic biopsy and transperineal MRI-targeted biopsy. Nineteen patients (17.8%) were upgraded to Gleason 4 + 3, three patients (3.0%) to Gleason 4 + 4 and one patient (1.0%) to Gleason 4 + 5. These differences were significant (P = 0.0006). Likewise, 23/107 patients (22%) had higher-risk disease based on their targeted biopsies. CONCLUSION: The use of targeted biopsy in men with impalpable cancer, ultimately upgraded one in five patients from favourable-intermediate- to unfavourable-intermediate-risk disease or worse. This has significant clinical implications for men considering active surveillance or radical treatment. Our risk calculators must now be validated using these data from targeted biopsy as the technique becomes widely adopted.

Prostate cancer heterogeneity: texture analysis score based on multiple magnetic resonance imaging sequences for detection, stratification and selection of lesions at time of biopsy.

OBJECTIVE: To undertake an early proof-of-concept study on a novel, semi-automated texture-based scoring system in order to enhance the association between magnetic resonance imaging (MRI) lesions and clinically significant prostate cancer (SPCa). PATIENTS AND METHODS: With ethics approval, 536 imaging volumes were generated from 20 consecutive patients who underwent multiparametric MRI (mpMRI) at time of biopsy. Volumes of interest (VOIs) included zonal anatomy segmentation and suspicious MRI lesions for cancer (Likert Scale score >2). Entropy (E), measuring heterogeneity, was computed from VOIs and plotted as a multiparametric score defined as the entropy score (ES) = E ADC + E Ktrans + E Ve + E T2WI. The reference test that was used to define the ground truth comprised systematic saturation biopsies coupled with MRI-targeted sampling. This generated 422 cores in all that were individually labelled and oriented in three-dimensions. Diagnostic accuracy for detection of SPCa, defined as Gleason score ≥3 + 4 or >3 mm of any grade of cancer on a single core, was assessed using receiver operating characteristics, correlation, and descriptive statistics. The proportion of cancerous lesions detected by ES and visual scoring (VS) were statistically compared using the paired McNemar test. RESULTS: Any cancer (Gleason score 6-8) was found in 12 of the 20 (60%) patients, with a median PSA level of 8.22 ng/mL. SPCa (mean [95% confidence interval, CI] ES = 17.96 [0.72] NATural information unit [NAT]) had a significantly higher ES than non-SPCa (mean [95% CI] ES = 15.33 [0.76] NAT). The ES correlated with Gleason score (rs = 0.568, P = 0.033) and maximum cancer core length (ρ = 0.781; P < 0.001). The area under the curve for the ES (0.89) and VS (0.91) were not significantly different (P = 0.75) for the detection of SPCa amongst MRI lesions. Best ES estimated numerical threshold of 16.61 NAT led to a sensitivity of 100% and negative predictive value of 100%. The proportion of MRI lesions that were found to be positive for SPCa using this ES threshold (54%) was significantly higher (P < 0.001) than using the VS (24% of score 3, 4, 5) in a paired analysis using the McNemar test. In all, 53% of MRI lesions would have avoided biopsy sampling without missing significant disease. CONCLUSION: Capturing heterogeneity of prostate cancer across multiple MRI sequences with the ES yielded high performances for the detection and stratification of SPCa. The ES outperformed the VS in predicting positivity of lesions, holding promise in the selection of targets for biopsy and calling for further understanding of this association.

Medium-term oncological outcomes in a large cohort of men treated with either focal or hemi-ablation using high-intensity focused ultrasonography for primary localized prostate cancer.

OBJECTIVE: To report medium-term oncological outcomes in men receiving primary focal treatment with high-intensity focused ultrasonography ( HIFU) for prostate cancer (PCa). PATIENTS AND METHODS: Consecutive patients with PCa treated with primary focal HIFU at two centres by six treating clinicians were assessed. Patients were submitted to either focal ablation or hemi-ablation using HIFU (Sonablate 500). The primary objective of the study was to assess medium-term oncological outcomes, defined as overall survival, freedom from biopsy failure, freedom from any further treatment and freedom from radical treatment after focal HIFU. The secondary objective was to evaluate the changes in pathological features among patients treated with focal HIFU over time. We also assessed the relationship between year of surgery and 5-year retreatment probability. RESULTS: A total of 1032 men treated between November 2005 and October 2017 were assessed. The median age was 65 years and median prostate-specific antigen level was 7 ng/mL. The majority of patients had a Gleason score of 3 + 4 or above (80.3%). The median (interquartile range) follow-up was 36 (14-64) months. The overall survival rates at 24, 60 and 96 months were 99%, 97% and 97%, respectively. Freedom from biopsy failure, defined as absence of Gleason 3 + 4 disease, was 84%, 64% and 54% at 24, 60 and 96 months. Freedom from any further treatment was 85%, 59% and 46% at 24, 60 and 96 months, respectively. Approximately 70% of patients who were retreated received a second focal treatment. Freedom from radical treatment was 98%, 91% and 81% at 24, 60 and 96 months. During the study period, we observed an increase in the proportion of patients undergoing focal HIFU with Gleason 3 + 4 disease and with T2 stage disease as defined by multiparametric magnetic resonance imaging. Finally, there was a reduction over time in the proportion of patients undergoing re-treatment within 5 years of first treatment. CONCLUSIONS: Focal HIFU for PCa is a feasible therapeutic strategy, with acceptable survival and oncological results and a reduction in the 5-year retreatment rates over the last decade. Re-do focal treatment is a feasible technique whose functional and oncological outcomes have still to be evaluated.

Role of MRI in planning radical prostatectomy: what is the added value?

INTRODUCTION: The goal of radical prostatectomy is to eradicate oncological disease while achieving the best possible functional outcomes. In this regard, nerve sparing offers a greater chance of recovering potency after surgery. Accurately locating prostate cancer foci is instrumental for identifying good candidates for this approach whilst maintaining safe oncological margins. In addition to this, the length of membranous urethra is an independent predictor of time to, and extent of, continence recovery. The introduction of Mp-MRI allows visualising malignant tissue within the prostate gland, which could lead to image-directed surgery planning as with other solid-organ cancers such as kidney, pancreas, breast or testes. METHODS: A narrative review of the available literature was performed. RESULTS: Mp-MRI demonstrated moderate sensitivity and high specificity to detect extra-capsular extension, seminal vesicle involvement or T3 stage. Measurements of membranous urethral length have shown to be useful in predicting probability of achieving continence after surgery. Furthermore, image-guided surgery has shown to be accurate to determine surgical planes to safely preserve neurovascular bundles. CONCLUSION: The use of Mp-MRI for pre-surgical planning introduces a new scenario where the previously homogeneous radical prostatectomy can be tailored to suit patient and tumour features. This has the potential to improve functional outcomes whilst not compromising on surgical margins. Moreover, the introduction of Mp-MRI increases the ability to predict functional outcomes after surgery and allows for a more accurate local staging. This in turn provides more information to both patients and clinicians in the decision-making process regarding treatment.

HistoScanningTM to Detect and Characterize Prostate Cancer-a Review of Existing Literature.

PURPOSE OF REVIEW: The widely acknowledged limitations of the standard prostate cancer (PCa) diagnostic paradigm have provided an impetus to explore novel imaging modalities to diagnose, localize, and risk stratify PCa. As the body of literature focused on HistoScanning™(HS) grows, there is need for a comprehensive review of the clinical efficacy of this technology. RECENT FINDINGS: Eighteen original, English language articles were found to adequately study the use of HistoScanning™ for prostate cancer diagnosis in the clinical setting. The articles were found by conducting a bibliographic search of PubMed in April 2017 in addition to utilizing references. The studies are divided into four groups based on study design. Study methods and quantitative data are summarized for each of the relevant articles. The results are synthesized to evaluate the utility of HistoScanning™ for the purpose of diagnosing PCa. Despite the promise of early pilot studies, there is a lack of consistent results across a number of further investigations of HistoScanning™. This becomes increasingly evident as study size increases. As various other modern diagnostic modalities continue to develop, the future of HistoScanning™, both alone and in conjunction with these technologies, remains unclear.

Image Guided Focal Therapy for Magnetic Resonance Imaging Visible Prostate Cancer: Defining a 3-Dimensional Treatment Margin Based on Magnetic Resonance Imaging Histology Co-Registration Analysis.

PURPOSE: We compared prostate tumor boundaries on magnetic resonance imaging and radical prostatectomy histological assessment using detailed software assisted co-registration to define an optimal treatment margin for achieving complete tumor destruction during image guided focal ablation. MATERIALS AND METHODS: Included in study were 33 patients who underwent 3 Tesla magnetic resonance imaging before radical prostatectomy. A radiologist traced lesion borders on magnetic resonance imaging and assigned a suspicion score of 2 to 5. Three-dimensional reconstructions were created from high resolution digitalized slides of radical prostatectomy specimens and co-registered to imaging using advanced software. Tumors were compared between histology and imaging by the Hausdorff distance and stratified by the magnetic resonance imaging suspicion score, Gleason score and lesion diameter. Cylindrical volume estimates of treatment effects were used to define the optimal treatment margin. RESULTS: Three-dimensional software based registration with magnetic resonance imaging was done in 46 histologically confirmed cancers. Imaging underestimated tumor size with a maximal discrepancy between imaging and histological boundaries for a given tumor of an average ± SD of 1.99 ± 3.1 mm, representing 18.5% of the diameter on imaging. Boundary underestimation was larger for lesions with an imaging suspicion score 4 or greater (mean 3.49 ± 2.1 mm, p <0.001) and a Gleason score of 7 or greater (mean 2.48 ± 2.8 mm, p = 0.035). A simulated cylindrical treatment volume based on the imaging boundary missed an average 14.8% of tumor volume compared to that based on the histological boundary. A simulated treatment volume based on a 9 mm treatment margin achieved complete histological tumor destruction in 100% of patients. CONCLUSIONS: Magnetic resonance imaging underestimates histologically determined tumor boundaries, especially for lesions with a high imaging suspicion score and a high Gleason score. A 9 mm treatment margin around a lesion visible on magnetic resonance imaging would consistently ensure treatment of the entire histological tumor volume during focal ablative therapy.

What tumours should we treat with focal therapy based on risk category, grade, size and location?

PURPOSE OF REVIEW: Focal therapy aims to reduce side-effects of active whole-gland therapies with an acceptable or noninferior oncologic benefit for the patient. The definition of the lesion to treat using this tissue-preserving approach is central, and there is a recent shift in considering more aggressive disease than in the past. This article examines recent consensus reports, assessment of emerging techniques, histologic considerations as well as results of trials and their development. RECENT FINDINGS: Accumulation of evidence reinforces the concept of clinically significant disease. Latest histologic assessment studies specify the index lesion characteristics. Index lesion localization was accurately evaluated by both multiparametric MRI (mpMRI)-targeted and transperineal mapping biopsy techniques against reference standard. mpMRI continues its development in accurate disease stratification. Development of new treatment modalities allows the clinician to investigate treatment of a lesion in various zonal anatomy locations. Consensus reports establish the intermediate risk population as the target for focal therapy, leaving very low risk disease to surveillance. Reviews of past clinical trials, including intermediate risk population, reveal encouraging oncologic follow-up. Ongoing trials will test focal therapy of index lesion with surveillance of insignificant secondary lesions. SUMMARY: Focal therapy should be investigated for intermediate risk population, leaving very low risk to surveillance. Detection and stratification techniques, namely mpMRI-targeted and transperineal biopsies, have an evolving role in lesion selection to confirm encouraging oncologic benefit for the patient.

Prostate tumour volumes: evaluation of the agreement between magnetic resonance imaging and histology using novel co-registration software.

OBJECTIVE: To evaluate the agreement between prostate tumour volume determined using multiparametric magnetic resonance imaging (MRI) and that determined by histological assessment, using detailed software-assisted co-registration. MATERIALS AND METHODS: A total of 37 patients who underwent 3T multiparametric MRI (T2-weighted imaging [T2WI], diffusion-weighted imaging [DWI]/apparent diffusion coefficient [ADC], dynamic contrast-enhanced [DCE] imaging) were included. A radiologist traced the borders of suspicious lesions on T2WI and ADC and assigned a suspicion score of between 2 and 5, while a uropathologist traced the borders of tumours on histopathological photographs. Software was used to co-register MRI and three-dimensional digital reconstructions of radical prostatectomy specimens and to compute imaging and histopathological volumes. Agreement in volumes between MRI and histology was assessed using Bland-Altman plots and stratified by tumour characteristics. RESULTS: Among 50 tumours, the mean differences (95% limits of agreement) in MRI relative to histology were -32% (-128 to +65%) on T2WI and -47% (-143 to +49%) on ADC. For all tumour subsets, volume underestimation was more marked on ADC maps (mean difference ranging from -57 to -16%) than on T2WI (mean difference ranging from -45 to +2%). The 95% limits of agreement were wide for all comparisons, with the lower 95% limit ranging between -77 and -143% across assessments. Volume underestimation was more marked for tumours with a Gleason score ≥7 or a MRI suspicion score 4 or 5. CONCLUSION: Volume estimates of prostate cancer using MRI tended to substantially underestimate histopathological volumes, with a wide variability in extent of underestimation across cases. These findings have implications for efforts to use MRI to guide risk assessment.

The Role of Multiparametric MRI and MRI-targeted Biopsy in the Diagnosis of Radiorecurrent Prostate Cancer: An Analysis from the FORECAST Trial.

BACKGROUND: The role of multiparametric magnetic resonance imaging (MRI) for detecting recurrent prostate cancer after radiotherapy is unclear. OBJECTIVE: To evaluate MRI and MRI-targeted biopsies for detecting intraprostatic cancer recurrence and planning for salvage focal ablation. DESIGN, SETTING, AND PARTICIPANTS: FOcal RECurrent Assessment and Salvage Treatment (FORECAST; NCT01883128) was a prospective cohort diagnostic study that recruited 181 patients with suspected radiorecurrence at six UK centres (2014 to 2018); 144 were included here. INTERVENTION: All patients underwent MRI with 5 mm transperineal template mapping biopsies; 84 had additional MRI-targeted biopsies. MRI scans with Likert scores of 3 to 5 were deemed suspicious. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: First, the diagnostic accuracy of MRI was calculated. Second, the pathological characteristics of MRI-detected and MRI-undetected tumours were compared using the Wilcoxon rank sum test and chi-square test for trend. Third, four biopsy strategies involving an MRI-targeted biopsy alone and with systematic biopsies of one to two other quadrants were studied. Fisher's exact test was used to compare MRI-targeted biopsy alone with the best other strategy for the number of patients with missed cancer and the number of patients with cancer harbouring additional tumours in unsampled quadrants. Analyses focused primarily on detecting cancer of any grade or length. Last, eligibility for focal therapy was evaluated for men with localised (≤T3bN0M0) radiorecurrent disease. RESULTS AND LIMITATIONS: Of 144 patients, 111 (77%) had cancer detected on biopsy. MRI sensitivity and specificity at the patient level were 0.95 (95% confidence interval [CI] 0.92 to 0.99) and 0.21 (95% CI 0.07 to 0.35), respectively. At the prostate quadrant level, 258/576 (45%) quadrants had cancer detected on biopsy. Sensitivity and specificity were 0.66 (95% CI 0.59 to 0.73) and 0.54 (95% CI 0.46 to 0.62), respectively. At the quadrant level, compared with MRI-undetected tumours, MRI-detected tumours had longer maximum cancer core length (median difference 3 mm [7 vs 4 mm]; 95% CI 1 to 4 mm, p < 0.001) and a higher grade group (p = 0.002). Of the 84 men who also underwent an MRI-targeted biopsy, 73 (87%) had recurrent cancer diagnosed. Performing an MRI-targeted biopsy alone missed cancer in 5/73 patients (7%; 95% CI 3 to 15%); with additional systematic sampling of the other ipsilateral and contralateral posterior quadrants (strategy 4), 2/73 patients (3%; 95% CI 0 to 10%) would have had cancer missed (difference 4%; 95% CI -3 to 11%, p = 0.4). If an MRI-targeted biopsy alone was performed, 43/73 (59%; 95% CI 47 to 69%) patients with cancer would have harboured undetected additional tumours in unsampled quadrants. This reduced but only to 7/73 patients (10%; 95% CI 4 to 19%) with strategy 4 (difference 49%; 95% CI 36 to 62%, p < 0.0001). Of 73 patients, 43 (59%; 95% CI 47 to 69%) had localised radiorecurrent cancer suitable for a form of focal ablation. CONCLUSIONS: For patients with recurrent prostate cancer after radiotherapy, MRI and MRI-targeted biopsy, with or without perilesional sampling, will diagnose cancer in the majority where present. MRI-undetected cancers, defined as Likert scores of 1 to 2, were found to be smaller and of lower grade. However, if salvage focal ablation is planned, an MRI-targeted biopsy alone is insufficient for prostate mapping; approximately three of five patients with recurrent cancer found on an MRI-targeted biopsy alone harboured further tumours in unsampled quadrants. Systematic sampling of the whole gland should be considered in addition to an MRI-targeted biopsy to capture both MRI-detected and MRI-undetected disease. PATIENT SUMMARY: After radiotherapy, magnetic resonance imaging (MRI) is accurate for detecting recurrent prostate cancer, with missed cancer being smaller and of lower grade. Targeting a biopsy to suspicious areas on MRI results in a diagnosis of cancer in most patients. However, for every five men who have recurrent cancer, this targeted approach would miss cancers elsewhere in the prostate in three of these men. If further focal treatment of the prostate is planned, random biopsies covering the whole prostate in addition to targeted biopsies should be considered so that tumours are not missed.

Prostate Imaging after Focal Ablation (PI-FAB): A Proposal for a Scoring System for Multiparametric MRI of the Prostate After Focal Therapy.

At present there is no standardised system for scoring the appearance of the prostate on multiparametric magnetic resonance imaging (MRI) after focal ablation for localised prostate cancer. We propose a novel scoring system, the Prostate Imaging after Focal Ablation (PI-FAB) score, to fill this gap. PI-FAB involves a 3-point scale for rating MRI sequences in sequential order: (1) dynamic contrast-enhanced sequences; (2) diffusion-weighted imaging, split into assessment of the high-b-value sequence first and then the apparent diffusion coefficient map; and (3) T2-weighted imaging. It is essential that the pretreatment scan is also available to help with this assessment. We designed PI-FAB using our experience of reading postablation scans over the past 15 years and include details for four representative patients initially treated with high-intensity focus ultrasound at our institution to demonstrate the scoring system. We propose PI-FAB as a standardised method for evaluating prostate MRI scans after treatment with focal ablation. The next step is to evaluate its performance across multiple experienced readers of MRI after focal therapy in a clinical data set. PATIENT SUMMARY: We propose a scoring system called PI-FAB for assessing the appearance of magnetic resonance imaging scans of the prostate after focal treatment for localised prostate cancer. This will help clinicians in deciding on further follow-up.

Diagnostic potential of radiological apical tumor involvement.

We commend Veerman et al. for investigating the diagnostic performance of radiological apical tumor involvement (radATI) in preoperative prostate magnetic resonance imaging (MRI) and its impact on clinical outcomes in patients with localized prostate cancer. This retrospective study evaluated the diagnostic accuracy of MRI to detect pathological ATI (pathATI) in robot-assisted radical prostatectomy specimens. They found patients with radATI more likely to develop biochemical recurrence (BCR), p = 0.003, and have apical positive surgical margins (APSM), p = 0.004. We believe that the author's acknowledgement of the relationship between tumor location and cancer risk is an important step in the classification of prostate cancer. An important question that is under addressed is, what is it about apical tumors that carry additional risk? Higher rates of PSM due to incomplete surgical excision may contribute to increased recurrence risk in the apex. If this is the case, surgical management must be tailored by a tumor location-based risk assessment. The literature suggests that a single APSM may be clinically insignificant for long-term outcomes. Conversely, the authors also recommend radATI be treated with reduced apical nerve sparing to avoid APSM. We believe that this approach may lead to overtreatment in the presence of an otherwise good prognosis. We believe the extent of APSMs upon diagnosis would be an interesting topic for further investigation. The authors may also wish to perform multivariable analysis for the effect of radATI on BCR. We believe that MRI may play a critical role in enhancing diagnosis and prognostication of prostate cancer.