Magnetic Resonance Imaging Targeted Biopsy Improves Selection of Patients Considered for Active Surveillance for Clinically Low Risk Prostate Cancer Based on Systematic Biopsies

Application of Advanced Imaging to Prostate Cancer Diagnosis and Management: A Narrative Review of Current Practice and Unanswered Questions

Major advances in prostate cancer diagnosis, staging, and management have occurred over the past decade, largely due to our improved understanding of the technical aspects and clinical applications of advanced imaging, specifically magnetic resonance imaging (MRI) and prostate-cancer-specific positron emission tomography (PET). Herein, we review the established utility of these important and exciting technologies, as well as areas of controversy and uncertainty that remain important areas for future study. There is strong evidence supporting the utility of MRI in guiding initial biopsy and assessing local disease. There is debate, however, regarding how to best use the imaging modality in risk stratification, treatment planning, and assessment of biochemical failure. Prostate-cancer-specific PET is a relatively new technology that provides great value to the evaluation of newly diagnosed, treated, and recurrent prostate cancer. However, its ideal use in treatment decision making, staging, recurrence detection, and surveillance necessitates further research. Continued study of both imaging modalities will allow for an improved understanding of their best utilization in improving cancer care.

Targeted Multiparametric Magnetic Resonance Imaging/Ultrasound Fusion Biopsy for Quantitative Gleason 4 Grading Prediction in Radical Prostatectomy Specimens: Implications for Active Surveillance Candidate Selection

BACKGROUND

Quantitative Gleason grading appears to be a reliable prognostic parameter and provides broader risk stratification then the traditional Gleason grading in patients with prostate cancer (PCa) treated with radical prostatectomy (RP).

OBJECTIVE

To determine if quantification of Gleason pattern (GP) 4 for targeted and systematic biopsy (TBx + SBx) cores together with further clinical variables can identify the lowest quantitative GP 4 fraction on RP.

DESIGN, SETTING, AND PARTICIPANTS

A total of 548 patients underwent TBx + SBx of the prostate and then RP, with pathology revealing Gleason score 3 + 4, 4 + 3, or 4 + 4 disease.

INTERVENTION

TBx + SBx of the prostate followed by RP.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

GP 4 fraction thresholds of ≤5%, ≤10%, ≤15%, ≤20%, and ≤25% were compared between the TBx + SBx and RP specimens. The sensitivity, specificity, negative predictive value (NPV), positive predictive value (PPV), and accuracy for predicting the GP 4 fraction in the RP specimen were determined. Logistic regression models were used to establish a probabilistic relationship between various combinations of clinical and biopsy variables and the GP 4 fraction in the RP specimen.

RESULTS AND LIMITATIONS

GP 4 fractions of ≤5%, ≤10%, ≤15%, ≤20%, and ≤25% was observed in 33%, 49%, 58%, 65%, and 70% of patients on TBx, and 18%, 41%, 53%, 63%, and 70% of patients on RP, respectively. The sensitivity, specificity, NPV, PPV, and accuracy were 75%, 67%, 91%, 39%, and 74% for a TBx GP 4 fraction of ≤5%, and 65%, 85%, 65%, 85%, and 79% for a TBx GP 4 fraction of ≤25%, respectively. A model combining quantified TBx + SBx GP 4 with clinical parameters demonstrated the highest diagnostic accuracy. Limitations include the retrospective study design.

CONCLUSIONS

Our results demonstrate that the combination of MRI-TBx + SBx and GP 4 quantification allowed precise detection of a low fraction of GP 4 when using RP specimens as the reference standard. Moreover, we found that clinical variables including Prostate Imaging-Reporting and Data System score without biopsy are limited in detection of low GP 4 fractions.

PATIENT SUMMARY

Combination of targeted biopsy alone as well as combined with systematic biopsy and quantitative Gleason grading of biopsy specimen showed high agreement with pathology findings after surgical removal of the prostate. This could help in identifying patients who are suitable for active surveillance.

The current role of MRI for guiding active surveillance in prostate cancer

Active surveillance (AS) is the recommended treatment option for low-risk and favourable intermediate-risk prostate cancer management, preserving oncological and functional outcomes. However, active monitoring using relevant parameters in addition to the usual clinical, biological and pathological considerations is necessary to compensate for initial undergrading of the tumour or to detect early progression without missing the opportunity to provide curative therapy. Indeed, several studies have raised concerns about inadequate biopsy sampling at diagnosis. However, the implementation of baseline MRI and targeted biopsy have led to improved initial stratification of low-risk disease; baseline MRI correlates well with disease characteristics and AS outcomes. The use of follow-up MRI during the surveillance phase also raises the question of the requirement for serial biopsies in the absence of radiological progression and the possibility of using completely MRI-based surveillance, with triggers for biopsies based solely on MRI findings. This concept of a tailored-risk, imaging-based monitoring strategy is aimed at reducing invasive procedures. However, the abandonment of serial biopsies in the absence of MRI progression can probably not yet be recommended in routine practice, as the data from real-life cohorts are heterogeneous and inconclusive. Thus, the evolution towards a routine, fully MRI-guided AS pathway has to be preceded by ensuring quality programme assessment for MRI reading and by demonstrating its safety in prospective trials.

Prostate Cancer Patients Under Active Surveillance with a Suspicious Magnetic Resonance Imaging Finding Are at Increased Risk of Needing Treatment: Results of the Movember Foundation's Global Action Plan Prostate Cancer Active Surveillance (GAP3) Consortium

BACKGROUND

The inclusion criterion for active surveillance (AS) is low- or intermediate-risk prostate cancer. The predictive value of the presence of a suspicious lesion at magnetic resonance imaging (MRI) at the time of inclusion is insufficiently known.

OBJECTIVE

To evaluate the percentage of patients needing active treatment stratified by the presence or absence of a suspicious lesion at baseline MRI.

DESIGN SETTING AND PARTICIPANTS

A retrospective analysis of the data from the multicentric AS GAP3 Consortium database was conducted. The inclusion criteria were men with grade group (GG) 1 or GG 2 prostate cancer combined with prostate-specific antigen <20 ng/ml. We selected a subgroup of patients who had MRI at baseline and for whom MRI results and targeted biopsies were used for AS eligibility. Suspicious MRI was defined as an MRI lesion with Prostate Imaging Reporting and Data System (PI-RADS)/Likert ≥3 and for which targeted biopsies did not exclude the patient for AS.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The primary outcome was treatment free survival (FS). The secondary outcomes were histological GG progression FS and continuation of AS (discontinuation FS).

RESULTS AND LIMITATIONS

The study cohort included 2119 patients (1035 men with nonsuspicious MRI and 1084 with suspicious MRI) with a median follow-up of 23 (12-43) mo. For the whole cohort, 3-yr treatment FS was 71% (95% confidence interval [CI]: 69-74). For nonsuspicious MRI and suspicious MRI groups, 3-yr treatment FS rates were, respectively, 80% (95% CI: 77-83) and 63% (95% CI: 59-66). Active treatment (hazard ratio [HR] = 2.0, p < 0.001), grade progression (HR = 1.9, p < 0.001), and discontinuation of AS (HR = 1.7, p < 0.001) were significantly higher in the suspicious MRI group than in the nonsuspicious MRI group.

CONCLUSIONS

The risks of switching to treatment, histological progression, and AS discontinuation are higher in cases of suspicious MRI at inclusion.

PATIENT SUMMARY

Among men with low- or intermediate-risk prostate cancer who choose active surveillance, those with suspicious magnetic resonance imaging (MRI) at the time of inclusion in active surveillance are more likely to show switch to treatment than men with nonsuspicious MRI.

Prediction of Grade Reclassification of Prostate Cancer Patients on Active Surveillance through the Combination of a Three-miRNA Signature and Selected Clinical Variables

Simple Summary

Active surveillance (AS) has evolved as an alternative to radical treatment for potentially indolent prostate cancer. However, current selection criteria for entering AS are suboptimal, and a significant percentage of patients discontinue AS because of disease reclassification. Hence, there is an unmet need for novel biomarkers for the accurate identification of high-risk PCa and the unequivocal classification of indolent disease. Circulating biomarkers, including microRNAs identified through liquid biopsies, represent a valuable approach to improve on currently available clinicopathological risk-stratification tools. In an attempt to identify specific microRNA signatures as potential circulating biomarkers, the authors performed an unprecedented analysis of the global microRNA profile in plasma samples from AS patients and identified and validated a three-microRNA signature able to predict patient reclassification. The addition of the three-microRNA signature was able to improve the performance of currently available clinicopathological variables, thus showing potential for the refinement of AS patients’ selection.

Abstract

Active surveillance (AS) has evolved as a strategy alternative to radical treatments for very low risk and low-risk prostate cancer (PCa). However, current criteria for selecting AS patients are still suboptimal. Here, we performed an unprecedented analysis of the circulating miRNome to investigate whether specific miRNAs associated with disease reclassification can provide risk refinement to standard clinicopathological features for improving patient selection. The global miRNA expression profiles were assessed in plasma samples prospectively collected at baseline from 386 patients on AS included in three independent mono-institutional cohorts (training, testing and validation sets). A three-miRNA signature (miR-511-5p, miR-598-3p and miR-199a-5p) was found to predict reclassification in all patient cohorts (training set: AUC 0.74, 95% CI 0.60–0.87, testing set: AUC 0.65, 95% CI 0.51–0.80, validation set: AUC 0.68, 95% CI 0.56–0.80). Importantly, the addition of the three-miRNA signature improved the performance of the clinical model including clinicopathological variables only (AUC 0.70, 95% CI 0.61–0.78 vs. 0.76, 95% CI 0.68–0.84). Overall, we trained, tested and validated a three-miRNA signature which, combined with selected clinicopathological variables, may represent a promising biomarker to improve on currently available clinicopathological risk stratification tools for a better selection of truly indolent PCa patients suitable for AS.

MRI-targeted prostate biopsy: the next step forward!

Aim

For decades, the gold standard technique for diagnosing prostate cancer was the 10 to 12 core systematic transrectal or transperineal biopsy, under ultrasound guidance. Over the past years, an increased rate of false negative results and detection of clinically insignificant prostate cancer has been noted, resulting into overdiagnosis and overtreatment. The purpose of the current study was to evaluate the changes in diagnosis and management of prostate cancer brought by MRI-targeted prostate biopsy.

Methods

A critical review of literature was carried out using the Medline database through a PubMed search, 37 studies meeting the inclusion criteria: prospective studies published in the past 8 years with at least 100 patients per study, which used multiparametric magnetic resonance imaging as guidance for targeted biopsies.

Results

In-Bore MRI targeted biopsy and Fusion targeted biopsy outperform standard systematic biopsy both in terms of overall and clinically significant prostate cancer detection, and ensure a lower detection rate of insignificant prostate cancer, with fewer cores needed. In-Bore MRI targeted biopsy performs better than Fusion biopsy especially in cases of apical lesions.

Conclusion

Targeted biopsy is an emerging and developing technique which offers the needed improvements in diagnosing clinically significant prostate cancer and lowers the incidence of insignificant ones, providing a more accurate selection of the patients for active surveillance and focal therapies.

The role of multiparametric magnetic resonance imaging in the selection and follow-up of patients undergoing active surveillance for prostate cancer. An European Section of Uro-Technology (ESUT) review

INTRODUCTION

In recent years, active surveillance (AS) has gained popularity as a safe and reasonable option for patients with low-risk, clinically localized prostate cancer.

OBJECTIVE

To summarize the latest information regarding the use of mpMRI in the setting of active surveillance (AS) for the management of prostate cancer (PCa).

EVIDENCE ACQUISITION

A PubMed-based, English literature search was conducted through February 2020. We selected the most relevant original articles, meta-analyses and systematic reviews that could provide important information.

EVIDENCE SYNTHESIS

The great importance of mpMRI of the prostate in the setting of PCa diagnosis is its ability to visualize primarily high-grade cancerous lesions potentially missed on systematic biopsies. In several studies, mpMRI has shown an improved performance over clinically based models for identifying candidates which will benefit the most from AS. Although data on prostate mpMRI during follow-up of men under AS is sparse, it holds the probability to improve significantly AS programs by a more precise selection of optimal candidates, a more accurate identification of disease progression and a reduction in number of biopsies. The goal of reassessment of patients undergoing AS is to find the most effective moment to change attitude to active treatment.

CONCLUSION

The value of mpMRI has been recognized due to its high negative predictive value (NPV) for lesion upgrading in low-risk PCa patients. The improvement in imaging detection, and precise diagnosis with mpMRI could reduce misclassifications at initial diagnosis and during follow-up, reducing the number of biopsies.

Advances in the selection of patients with prostate cancer for active surveillance

Early identification and management of prostate cancer completely changed with the discovery of prostate-specific antigen. However, improved detection has also led to overdiagnosis and consequently overtreatment of patients with low-risk disease. Strategies for the management of patients using active surveillance - the monitoring of clinically insignificant disease until intervention is warranted - were developed in response to this issue. The success of this approach is critically dependent on the accurate selection of patients who are predicted to be at the lowest risk of prostate cancer mortality. The Epstein criteria for clinically insignificant prostate cancer were first published in 1994 and have been repeatedly validated for risk-stratification and selection for active surveillance over the past few decades. Current active surveillance programmes use modified criteria with 30-50% of patients receiving treatment at 10 years. Nonetheless, tools for prostate cancer diagnosis have continued to evolve with improvements in biopsy format and targeting, advances in imaging technologies such as multiparametric MRI, and the identification of serum-, tissue- and urine-based biomarkers. These advances have the potential to further improve the identification of men with low-risk disease who can be appropriately managed using active surveillance.

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.

Prostate MRI with PI-RADS v2.1: initial detection and active surveillance

The role of prostate MRI in clinical practice has continued to broaden over time. Multiple iterations of PI-RADS reporting have aided in improving detection and reporting of prostate cancer. In addition, recent recommendations from the PI-RADS Steering Committee promote an MRI-first approach with an MRI-directed prostate cancer diagnostic pathway. It is imperative for radiologists to be knowledgeable and familiar with prostate MRI and PI-RADS recommendations, as there is an increasing demand for prostate imaging by clinicians and patients alike.

[Predictive factors of active surveillance interruption for prostate cancer after 5years of follow-up]

INTRODUCTION AND PURPOSE

The objective of this work was to identify the risk factors (RFs) of active surveillance (AS) interruption in a prostate cancer (PCa) single-center retrospective cohort of patients.

MATERIAL AND METHOD

All patients in AS between January 2011 and October 2019 were retrospectively included in a computerized database. The group of patients who had an AS interruption was compared to the one still under AS, in order to identify potential risk factors for the interruption of the surveillance protocol.

RESULTS

Two hundred and two patients have been included in the AS cohort with a median follow-up of 32months. At the time of analysis, 72 patients (36%) were not under the AS protocol anymore, 118 (58%) were still under AS and 12 (6%) were lost of follow-up. Sixty-six patients (92%) had left SA due to PCa progression, 4 (5%) by personal choice and 2 (3%) switched to watchful waiting. A PSA doubling Time<3years (PSADT<3years) has been identified as the only statistically significant RF for AS interruption, both in the unvaried (P<0.001) and multivariate (OR=5.403, P<0.01) analysis. It was also the only RF of AS interruption in the early analysis in the first three years of AS, in the unvaried analysis (P=0.021) and the multivariate analysis (OR=3.612, P=0.018).

CONCLUSION

PSADT was the only RF of AS early and late interruption in our study. It represents a major inclusion criterion in AS protocol during the initial assessment.

LEVEL OF EVIDENCE

3.

Prostate cancer upgrading with serial prostate magnetic resonance imaging and repeat biopsy in men on active surveillance: are confirmatory biopsies still necessary?

Objectives

To investigate whether serial prostate magnetic resonance imaging (MRI) may guide the utility of repeat targeted (TBx) and systematic biopsy (SBx) when monitoring men with low‐risk prostate cancer (PCa) at 1‐year of active surveillance (AS).

Patients and Methods

We retrospectively included 111 consecutive men with low‐risk (International Society of Urological Pathology [ISUP] Grade 1) PCa, who received protocolled repeat MRI with or without TBx and repeat SBx at 1‐year of AS. TBx was performed in Prostate Imaging‐Reporting and Data System (PI‐RADS) score ≥3 lesions (MRI‐positive men). Upgrading defined as ISUP Grade ≥2 PCa (I), Grade ≥2 with cribriform growth/intraductal carcinoma PCa (II), and Grade ≥3 PCa (III) was investigated. Upgrading detected by TBx only (not by SBx) and SBx only (not by TBx) was investigated in MRI‐positive and ‐negative men, and related to radiological progression on MRI (Prostate Cancer Radiological Estimation of Change in Sequential Evaluation [PRECISE] score).

Results

Overall upgrading (I) was 32% (35/111). Upgrading in MRI‐positive and ‐negative men was 48% (30/63) and 10% (5/48) (P < 0.001), respectively. In MRI‐positive men, there was upgrading in 23% (seven of 30) by TBx only and in 33% (10/30) by SBx only. Radiological progression (PRECISE score 4–5) in MRI‐positive men was seen in 27% (17/63). Upgrading (I) occurred in 41% (seven of 17) of these MRI‐positive men, while this was 50% (23/46) in MRI‐positive men without radiological progression (PRECISE score 1–3) (P = 0.534). Overall upgrading (II) was 15% (17/111). Upgrading in MRI‐positive and ‐negative men was 22% (14/63) and 6% (three of 48) (P = 0.021), respectively. In MRI‐positive men, there was upgrading in three of 14 by TBx only and in seven of 14 by SBx only. Overall upgrading (III) occurred in 5% (five of 111). Upgrading in MRI‐positive and ‐negative men was 6% (four of 63) and 2% (one of 48) (P = 0.283), respectively. In MRI‐positive men, there was upgrading in one of four by TBx only and in two of four by SBx only.

Conclusion

Upgrading is significantly lower in MRI‐negative compared to MRI‐positive men with low‐risk PCa at 1‐year of AS. In serial MRI‐negative men, the added value of repeat SBx at 1‐year surveillance is limited and should be balanced individually against the harms. In serial MRI‐positive men, the added value of repeat SBx is substantial. Based on this cohort, SBx is recommended to be performed in combination with TBx in all MRI‐positive men at 1‐year of AS, also when there is no radiological progression.

Update of the Standard Operating Procedure on the Use of Multiparametric Magnetic Resonance Imaging for the Diagnosis, Staging and Management of Prostate Cancer

PURPOSE

We update the prior standard operating procedure for magnetic resonance imaging of the prostate, and summarize the available data about the technique and clinical use for the diagnosis and management of prostate cancer. This update includes practical recommendations on the use of magnetic resonance imaging for screening, diagnosis, staging, treatment and surveillance of prostate cancer.

MATERIALS AND METHODS

A panel of clinicians from the American Urological Association and Society of Abdominal Radiology with expertise in the diagnosis and management of prostate cancer evaluated the current published literature on the use and technique of magnetic resonance imaging for this disease. When adequate studies were available for analysis, recommendations were made on the basis of data and when adequate studies were not available, recommendations were made on the basis of expert consensus.

RESULTS

Prostate magnetic resonance imaging should be performed according to technical specifications and standards, and interpreted according to standard reporting. Data support its use in men with a previous negative biopsy and ongoing concerns about increased risk of prostate cancer. Sufficient data now exist to support the recommendation of magnetic resonance imaging before prostate biopsy in all men who have no history of biopsy. Currently, the evidence is insufficient to recommend magnetic resonance imaging for screening, staging or surveillance of prostate cancer.

CONCLUSIONS

Use of prostate magnetic resonance imaging in the risk stratification, diagnosis and treatment pathway of men with prostate cancer is expanding. When quality prostate imaging is obtained, current evidence now supports its use in men at risk of harboring prostate cancer and who have not undergone a previous biopsy, as well as in men with an increasing prostate specific antigen following an initial negative standard prostate biopsy procedure.

Development and External Validation of Multiparametric MRI-Derived Nomogram to Predict Risk of Pathologic Upgrade in Patients on Active Surveillance for Prostate Cancer

OBJECTIVE. The aim of this study was to create, develop, and externally validate a nomogram that predicts pathologic upgrade in patients on active surveillance (AS) for prostate cancer using commonly available clinical and multiparametric MRI (mpMRI) factors. MATERIALS AND METHODS. A consecutive sample of 300 patients undergoing AS for prostate cancer at the Keimyung University Dongsan Hospital between 2010 and 2016 was used to develop the nomogram. The validation cohort consisted of 150 patients undergoing active surveillance at Kyungpook National University Hospital between 2013 and 2017. The study outcome was the occurrence of pathologic upgrade in AS patients. The relationship between the clinical and mpMRI factors considered and pathologic upgrade was tested using univariate and multivariate logistic regression analyses. The predictive accuracy of the nomogram was determined using the ROC AUC. RESULTS. The overall rate of pathologic upgrade was 25.0% in the developmental cohort and 22.0% in the validation cohort. Significant variables in the models were age, prostate-specific antigen level, biopsy grade group 2, baseline Prostate Imaging Reporting and Data System (PI-RADS) scores of 4 and 5, positive cores on initial biopsy greater than 1, and biopsy cores with 50% or more tumor involvement. The progression seen on mpMRI of PI-RADS score was significantly associated with pathologic upgrade. The nomogram used to predict the risk of pathologic upgrade had a predictive accuracy of 0.78 in the external validation cohort. CONCLUSION. This study developed and externally validated a nomogram that predicts the risk of pathologic upgrade on the basis of commonly used factors. This nomogram may be used to assist management decision making for patients on AS for prostate cancer.

Decreased accuracy of the prostate cancer EAU risk group classification in the era of imaging-guided diagnostic pathway: proposal for a new classification based on MRI-targeted biopsies and early oncologic outcomes after surgery

PURPOSE

To assess the performance of EAU risk classification in PCa patients according to the biopsy pathway (standard versus MRI guided) and to develop a new, more accurate, targeted biopsy (TB)-based classification.

MATERIALS AND METHODS

We included 1345 patients consecutively operated by radical prostatectomy (RP) since 2014, when MRI and TB were introduced in the diagnostic pathway. Patients underwent systematic biopsy (SB) only (n = 819) or SB and TB (n = 526) prior to RP during the same time period. Pathological and biochemical outcomes were compared between PCa men undergoing SB (SB cohort) and a combination of TB and SB (TB cohort). Kaplan-Meier and Cox regression models were used to assess biochemical recurrence-free survival (RFS).

RESULTS

Both cohorts were comparable regarding final pathology and RFS (p = 0.538). The EAU risk classification accurately predicted outcomes in SB cohort, but did not significantly separate low from intermediate risk in TB cohort (p = 0.791). In TB cohort, the new proposed three-group risk classification significantly improved the recurrence risk prediction compared with the EAU risk classification: HR 4 (versus HR 1.2, p = 0.009) for intermediate, and HR 15 (versus HR 6.5, p < 0.001) in high-risk groups, respectively. A fourth group defining very high-risk cases (≥ T2c clinical stage or grade group 5) was also proposed.

CONCLUSIONS

The new classification integrating TB findings we propose meaningfully improves the recurrence prediction after surgery in patients undergoing a TB-based diagnostic pathway, compared with standard EAU risk classification which is still relevant for patients undergoing only SB. External validation is needed.

Automatic segmentation of prostate MRI using convolutional neural networks: Investigating the impact of network architecture on the accuracy of volume measurement and MRI-ultrasound registration

Convolutional neural networks (CNNs) have recently led to significant advances in automatic segmentations of anatomical structures in medical images, and a wide variety of network architectures are now available to the research community. For applications such as segmentation of the prostate in magnetic resonance images (MRI), the results of the PROMISE12 online algorithm evaluation platform have demonstrated differences between the best-performing segmentation algorithms in terms of numerical accuracy using standard metrics such as the Dice score and boundary distance. These small differences in the segmented regions/boundaries outputted by different algorithms may potentially have an unsubstantial impact on the results of downstream image analysis tasks, such as estimating organ volume and multimodal image registration, which inform clinical decisions. This impact has not been previously investigated. In this work, we quantified the accuracy of six different CNNs in segmenting the prostate in 3D patient T2-weighted MRI scans and compared the accuracy of organ volume estimation and MRI-ultrasound (US) registration errors using the prostate segmentations produced by different networks. Networks were trained and tested using a set of 232 patient MRIs with labels provided by experienced clinicians. A statistically significant difference was found among the Dice scores and boundary distances produced by these networks in a non-parametric analysis of variance (p < 0.001 and p < 0.001, respectively), where the following multiple comparison tests revealed that the statistically significant difference in segmentation errors were caused by at least one tested network. Gland volume errors (GVEs) and target registration errors (TREs) were then estimated using the CNN-generated segmentations. Interestingly, there was no statistical difference found in either GVEs or TREs among different networks, (p = 0.34 and p = 0.26, respectively). This result provides a real-world example that these networks with different segmentation performances may potentially provide indistinguishably adequate registration accuracies to assist prostate cancer imaging applications. We conclude by recommending that the differences in the accuracy of downstream image analysis tasks that make use of data output by automatic segmentation methods, such as CNNs, within a clinical pipeline should be taken into account when selecting between different network architectures, in addition to reporting the segmentation accuracy.

Outcomes of Serial Multiparametric Magnetic Resonance Imaging and Subsequent Biopsy in Men with Low-risk Prostate Cancer Managed with Active Surveillance

BACKGROUND

Outcomes of serial multiparametric magnetic resonance imaging (mpMRI) and subsequent biopsy in monitoring prostate cancer (PCa) in men on active surveillance (AS) have not been defined clearly.

OBJECTIVE

To determine whether changes in serial mpMRI can predict pathological upgrade among men with grade group (GG) 1 PCa managed with AS.

DESIGN, SETTING, AND PARTICIPANTS

Retrospective analysis of men with GG1 on AS with at least two consecutive mpMRI examinations during 2012-2018 who underwent mpMRI/ultrasound fusion or systematic biopsies.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Progression on serial mpMRI was evaluated as a predictor of pathological upgrading to GG≥2 on a follow-up biopsy using clinical, pathological, and imaging factors in binary logistic regression. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were determined.

RESULTS AND LIMITATIONS

Of 122 patients, 29 men (23.8%) experienced pathological upgrade on the follow-up biopsy. Progression on mpMRI was not associated with pathological upgrade. The sensitivity, specificity, PPV, and NPV of mpMRI progression for predicting pathological upgrade were 41.3%, 54.8%, 22.2%, and 75%, respectively. Age (odds ratio [OR] 1.17, p=0.006), Prostate Imaging Reporting and Data System (PI-RADS) score on initial mpMRI (4-5 vs ≤3, OR 7.48, p=0.01), number of positive systematic cores (OR 1.84, p=0.03), number of positive targeted cores (OR 0.44, p=0.04), and maximum percent of targeted core tumor involvement (OR 1.04, p=0.01) were significantly associated with pathological upgrade.

CONCLUSIONS

We did not observe an association between mpMRI progression and pathological upgrade; however, a PI-RADS score of 4-5 on initial mpMRI was predictive of subsequent pathological progression. The continued use of systematic and fusion biopsies appears necessary due to risks of reclassification over time.

PATIENT SUMMARY

Progression on serial multiparametric magnetic resonance imaging during active surveillance (AS) is not associated with progression on the follow-up biopsy. Both systematic and fusion biopsies are necessary to sufficiently capture progression during AS.

National Survey of Patterns Employing Targeted MRI/US Guided Prostate Biopsy in the Diagnosis and Staging of Prostate Cancer

Background/aims

Targeted magnetic resonance imaging/ ultrasound (MRI/US) guided biopsy is an emerging technology that has the potential to change standard of care for the diagnosis and management of prostate cancer. This technology is rapidly proliferating, however quantitative analysis of these trends are unavailable. The objective of this study was to assess urologist opinions regarding implementing MRI/ US imaging into their practices.

Methods

A questionnaire was distributed using research electronic data capture and completed by 291 practicing urologists within the United States registered through the American Urological Association. The survey gathered information regarding demographics, changes in MRI use, opinions on targeted MRI/US guided biopsy, and barriers to implementation. The survey results were analyzed using ANOVA.

Results

Practice setting and geographic region were signifIcantly associated with implementation of MRI/US guided biopsy. Total 72% of urologists in academic centers report using MRI/US targeted biopsy, compared to 38% in solo private practice. In the northeast 68% of urologists report using MRI/US biopsy, compared to 44% in the western United States.

Conclusion

While there are some reservations about employing MRI/US guided biopsy as standard of care in all prostate biopsies, the data suggests urologists support its use, and are making efforts to introduce targeted MRI/US guided biopsy into their practice. Regional and practice setting variations exist in implementation.

Imaging as a Personalized Biomarker for Prostate Cancer Risk Stratification

Biomarkers provide objective data to guide clinicians in disease management. Prostate-specific antigen serves as a biomarker for screening of prostate cancer but has come under scrutiny for detection of clinically indolent disease. Multiple imaging techniques demonstrate promising results for diagnosing, staging, and determining definitive management of prostate cancer. One such modality, multiparametric magnetic resonance imaging (mpMRI), detects more clinically significant disease while missing lower volume and clinically insignificant disease. It also provides valuable information regarding tumor characteristics such as location and extraprostatic extension to guide surgical planning. Information from mpMRI may also help patients avoid unnecessary biopsies in the future. It can also be incorporated into targeted biopsies as well as following patients on active surveillance. Other novel techniques have also been developed to detect metastatic disease with advantages over traditional computer tomography and magnetic resonance imaging, which primarily rely on defined size criteria. These new techniques take advantage of underlying biological changes in prostate cancer tissue to identify metastatic disease. The purpose of this review is to present literature on imaging as a personalized biomarker for prostate cancer risk stratification.

Does the introduction of prostate multiparametric magnetic resonance imaging into the active surveillance protocol for localized prostate cancer improve patient re-classification?

OBJECTIVES

To determine whether replacement of protocol-driven repeat prostate biopsy (PB) with multiparametric magnetic resonance imaging (mpMRI) ± repeat targeted prostate biopsy (TB) when evaluating men on active surveillance (AS) for low-volume, low- to intermediate-risk prostate cancer (PCa) altered the likelihood of or time to treatment, or reduced the number of repeat biopsies required to trigger treatment.

PATIENTS AND METHODS

A total of 445 patients underwent AS in the period 2010-2016 at our institution, with a median (interquartile range [IQR]) follow-up of 2.4 (1.2-3.7) years. Up to 2014, patients followed a 'pre-2014' AS protocol, which incorporated PB, and subsequently, according to the 2014 National Institute for Health and Care Excellence (NICE) guidelines, patients followed a '2014-present' AS protocol that included mpMRI. We identified four groups of patients within the cohort: 'no mpMRI and no PB'; 'PB alone'; 'mpMRI ± TB'; and 'PB and mpMRI ± TB'. Kaplan-Meier plots and log-rank tests were used to compare groups.

RESULTS

Of 445 patients, 132 (30%) discontinued AS and underwent treatment intervention, with a median (IQR) time to treatment of 1.55 (0.71-2.4) years. The commonest trigger for treatment was PCa upgrading after mpMRI and TB (43/132 patients, 29%). No significant difference was observed in the time at which patients receiving a PB alone or receiving mpMRI ± TB discontinued AS to undergo treatment (median 1.9 vs 1.33 years; P = 0.747). Considering only those patients who underwent repeat biopsy, a greater proportion of patients receiving TB after mpMRI discontinued AS compared with those receiving PB alone (29/66 [44%] vs 32/87 [37%]; P = 0.003). On average, a single set of repeat biopsies was needed to trigger treatment regardless of whether this was a PB or TB.

CONCLUSIONS

Replacing a systematic PB with mpMRI ±TB as part of an AS protocol increased the likelihood of re-classifying patients on AS and identifying men with clinically significant disease requiring treatment. mpMRI ±TB as part of AS thereby represents a significant advance in the oncological safety of the AS protocol.

Entering an era of radiogenomics in prostate cancer risk stratification

Radiogenomics is a field that amalgamates data from genomics and imaging techniques in order to derive clinically meaningful trends. In this article, we discuss the importance of prostate cancer risk classification and how data derived from genomic testing and multi-parametric magnetic resonance imaging (mpMRI) can be integrated into clinical decision-making processes with a focus on active surveillance (AS). Finally, we describe an ongoing prospective trial (Miami MAST trial) which incorporates imaging (mpMRI) and radiomics data in patients who are on AS for prostate cancer.

MRI findings guiding selection of active surveillance for prostate cancer: a review of emerging evidence

Active surveillance (AS) for prostate cancer (PCa) is generally considered to be a safe strategy for men with low-risk, localized disease. However, as many as 1 in 4 patients may be incorrectly classified as AS-eligible using traditional inclusion criteria. The use of multiparametric magnetic resonance imaging (mpMRI) may offer improved risk stratification in both the initial diagnostic and disease monitoring setting. We performed a review of recently published studies to evaluate the utility of this imaging modality for this clinical setting. An English literature search was conducted on PubMed for original investigations on localized PCa, AS, and magnetic resonance imaging. Our Boolean criteria included the following terms: PCa, AS, imaging, MRI, mpMRI, prospective, retrospective, and comparative. Our search excluded publication types such as comments, editorials, guidelines, reviews, or interviews. Our literature review identified 71 original investigations. Among these, 52 met our inclusion criteria. Evidence suggests mpMRI improves characterization of clinically significant prostate cancer (csPCa) foci, and the enhanced detection and risk-stratification afforded by this modality may keep men from being inappropriately placed on AS. Use of serial mpMRI may also permit longer intervals between confirmatory biopsies. Multiple studies demonstrate the benefit of MRI-targeted biopsies. The use of mpMRI of the prostate offers improved confidence in risk-stratification for men with clinically low-risk PCa considering AS. While on AS, serial mpMRI and MRI-targeted biopsy aid in the detection of aggressive disease transformation or foci of clinically-significant cancer undetected on prior biopsy sessions.

How Would MRI-targeted Prostate Biopsy Alter Radiation Therapy Approaches in Treating Prostate Cancer?

OBJECTIVE

To determine if magnetic resonance imaging (MRI)/ultrasound fusion-targeted prostate biopsy (TB) would lead to increased recommendations of aggressive radiotherapy treatments for higher risk prostate cancer compared to systematic biopsy (SB) results.

METHODS

Clinicopathologic data of 533 men who underwent both TB and SB from 2014 to 2017 was analyzed. TB was performed in addition to SB in patients with detection of MRI suspicious lesions. Three patient cohorts were established: (1) biopsy naïve (80/533, 15.0%), (2) active surveillance (185/533, 34.7%), and (3) prior negative biopsy (268/533, 50.3%). Cancer risk categorical criteria were established with recommended radiotherapy treatment for each. Variation of risk classification due to biopsy method for all patients and within each cohort was analyzed using either a chi-squared statistic or Fisher's exact test. McNemar's pairwise analyses were performed for all risk categories between TB and SB to assess the effects of TB on high-risk cancer identification and subsequent radiotherapy recommendations.

RESULTS

Number of patients within cancer risk categories (1. "No Cancer or Low-Risk"; 2. "More Favorable Intermediate-Risk"; 3. "Less Favorable Intermediate-Risk"; 4. "High-Risk") varied significantly based on TB and SB pathology among all patients combined (P <.0001), in cohort 2 (P = .0005), and in cohort 3 (P <0.0001). Further, among all patients, TB increased cancer risk classification and correspondingly would result in more aggressive radiotherapy recommendations: "No Cancer or Low-Risk" to "Less Favorable Intermediate-Risk" (30/343, P <0.0001) and "No Cancer or Low-Risk" to "High-Risk" (31/353, P <.0001).

CONCLUSION

Among men with prostate cancer, TB commonly led to reclassification to a higher risk group, which is accompanied by more aggressive radiotherapy treatment recommendations when compared with SB findings alone.

MRI in active surveillance: a critical review

INTRODUCTION

Recent technological advancements and the introduction of modern anatomical and functional sequences have led to a growing role for multiparametric magnetic resonance imaging (mpMRI) in the detection, risk assessment and monitoring of early prostate cancer. This includes men who have been diagnosed with lower-risk prostate cancer and are looking at the option of active surveillance (AS). The purpose of this paper is to review the recent evidence supporting the use of mpMRI at different time points in AS, as well as to discuss some of its potential pitfalls.

METHODS

A combination of electronic and manual searching methods were used to identify recent, important papers investigating the role of mpMRI in AS.

RESULTS

The high negative predictive value of mpMRI can be exploited for the selection of AS candidates. In addition, mpMRI can be efficiently used to detect higher risk disease in patients already on surveillance.

CONCLUSION

Although there is an ongoing debate regarding the precise nature of its optimal implementation, mpMRI is a promising risk stratification tool and should be considered for men on AS.

Association Between Prostate Magnetic Resonance Imaging and Observation for Low-risk Prostate Cancer

OBJECTIVE

To evaluate the association between prostate magnetic resonance imaging (MRI) and the use of observation for men with low-risk prostate cancer (PCa).

MATERIALS AND METHODS

We used the Surveillance, Epidemiology, and End Results-Medicare database to identify men diagnosed with low-risk PCa during 2010-2013. We assessed the use of prostate MRI and management using claims in period surrounding PCa diagnosis. The relation of clinical and demographic factors to receipt of MRI was evaluated with multivariable logistic regression analysis. Following propensity score matching, we fit conditional logistic regression models to examine the association between prostate MRI and initial management, ie, observation or definitive treatment.

RESULTS

Of 8144 patients with low-risk PCa, 495 (6.1%) received MRI. Use of MRI increased from 3.4% in 2010 to 10.5% in 2013. A total of 3060 (37.6%) patients received observation. MRI was performed in 265 (8.7%) of patients receiving observation, and 230 (4.5%) who were treated (P < .0001). In multivariable analysis, measures of socioeconomic status were significantly associated with the use of prostate MRI. Following propensity score matching, receipt of prostate MRI surrounding the diagnosis of PCa was associated with a significantly higher likelihood of observation (odds ratio = 1.90, 95% confidence interval: 1.56-2.32). This effect persisted in sensitivity analyses attempting to exclude treatment-planning MRIs.

CONCLUSION

Receipt of prostate MRI surrounding PCa diagnosis was associated with a nearly 2-fold greater odds of receiving observation vs definitive treatment.

Low-risk prostate cancer selected for active surveillance with negative MRI at entry: can repeat biopsies at 1 year be avoided? A pilot study

PURPOSE

In patients considered for active surveillance (AS), the use of MRI and targeted biopsies (TB) at entry challenges the approach of routine "per protocol" repeat systematic biopsies (SB) at 1 year. This pilot study aimed to assess whether an approach of performing repeat biopsies only if PSA kinetics are abnormal would be safe and sufficient to detect progression.

METHODS

Prospective single-centre study of 149 patients on AS with low-risk PCa, a negative MRI at entry, followed for a minimum of 12 months between 01/2007 and 12/2015. Group 1 (n = 78) patients had per-protocol 12-month repeat SB; group 2 (n = 71) patients did not. Surveillance tests for tumour progression were for both groups: for cause SB and MRI-TB biopsies if PSA velocity (PSA-V) > 0.75 ng/ml/year, or PSA doubling time (PSADT) < 3 years. The main objectives are to compare the 2-year rates of tumour progression and AS discontinuation between groups. The secondary objectives are to estimate the diagnostic power of PSA-V and PSA-DT, to predict the risk of tumour progression.

RESULTS

Overall, 21 out of 149 patients (14.1%) showed tumour progression, 17.1% for group 1 and 12.3% for group 2, and 31 (21.2%) discontinued AS at 2 years. There was no difference between the 2 groups (p = 0.56). The area under the PSA-V and PSADT curves to predict tumour progression was 0.92 and 0.83, respectively.

CONCLUSIONS

We did not find any significant difference for progression and AS discontinuation rate between the 2 groups. The PSA kinetic seems accurate as a marker of tumour progression. These results support the conduct of a multi-centre prospective trial to confirm these findings.

Progression and treatment rates using an active surveillance protocol incorporating image-guided baseline biopsies and multiparametric magnetic resonance imaging monitoring for men with favourable-risk prostate cancer

OBJECTIVE

To assess early outcomes since the introduction of an active surveillance (AS) protocol incorporating multiparametric magnetic resonance imaging (mpMRI)-guided baseline biopsies and image-based surveillance.

PATIENTS AND METHODS

A new AS protocol mandating image-guided baseline biopsies, annual mpMRI and 3-monthly prostate-specific antigen (PSA) testing, but which retained protocol re-biopsies, was tested. Pathological progression, treatment conversion and triggers for non-protocol biopsy were recorded prospectively.

RESULTS

Data from 157 men enrolled in the AS protocol (median age 64 years, PSA 6.8 ng/mL, follow-up 39 months) were interrogated. A total of 12 men (7.6%) left the AS programme by choice. Of the 145 men who remained, 104 had re-biopsies either triggered by a rise in PSA level, change in mpMRI findings or by protocol. Overall, 23 men (15.9%) experienced disease progression; pathological changes were observed in 20 men and changes in imaging results were observed in three men. Of these 23 men, 17 switched to treatment, giving a conversion rate of 11.7% (<4% per year). Of the 20 men with pathological progression, this was detected in four of them after a PSA increase triggered a re-biopsy, while in 10 men progression was detected after an mpMRI change. Progression was detected in six men, however, solely after a protocol re-biopsy without prior PSA or mpMRI changes. Using PSA and mpMRI changes alone to detect progression was found to have a sensitivity and specificity of 70.0% and 81.7%, respectively.

CONCLUSION

Our AS protocol, with thorough baseline assessment and imaging-based surveillance, showed low rates of progression and treatment conversion. Changes in mpMRI findings were the principle trigger for detecting progression by imaging alone or pathologically; however, per protocol re-biopsy still detected a significant number of pathological progressions without mpMRI or PSA changes.

Is magnetic resonance imaging-targeted biopsy a useful addition to systematic confirmatory biopsy in men on active surveillance for low-risk prostate cancer? A systematic review and meta-analysis

OBJECTIVE

To systematically review and meta-analyse evidence regarding the additional value of magnetic resonance imaging (MRI) and MRI-targeted biopsies to confirmatory systematic biopsies in identifying high-grade prostate cancer in men with low-risk disease on transrectal ultrasonography (TRUS) biopsy, as active surveillance (AS) of prostate cancer is recommended for men with Gleason 3 + 3 on standard TRUS-guided biopsy. Confirmatory assessment can include repeat standard TRUS-guided biopsy, and/or MRI with targeted biopsy when indicated.

METHODS

A systematic review of the Embase, Medline, Web-of-science, Google scholar, and Cochrane library was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Identified reports were critically appraised according to the Quality Assessment of Diagnostic Accuracy Studies (QUADAS)-2 criteria. Studies reporting men with Gleason 3 + 3 prostate cancer who had chosen AS based on transrectal systematic biopsy findings and had undergone MRI with systematic ± targeted biopsy at confirmatory assessment were included. The primary outcome was detection of any Gleason pattern ≥4.

RESULTS

Included reports (six) of men on AS (n = 1 159) showed cancer upgrading (Gleason ≥3 + 4) in 27% (95% confidence interval [CI] 22-34%) using a combined approach of MRI-targeted biopsies and confirmatory systematic biopsies. MRI-targeted biopsies alone would have missed cancer upgrading in 10% (95% CI 8-14%) and standard biopsies alone would have missed cancer upgrading in 7% (95% CI 5-10%). No pathway was more favourable than the other (relative risk [RR] 0.92, 95% CI 0.79-1.06). In all, 35% (95% CI 27-43%) of men with a positive MRI were upgraded, compared to 12% (95% CI 8-18%) of men with a negative MRI being upgraded (RR 2.77, 95% CI 1.76-4.38).

CONCLUSIONS

A pre-biopsy MRI should be performed before confirmatory systematic TRUS-guided biopsies in men on AS, together with MRI-targeted biopsies when indicated. A combined approach maximises cancer detection, although other factors within multivariate risk prediction can be used to aid the decision to biopsy in these men.

[Active surveillance in prostate cancer: Assessment of MRI in the selection and follow-up of patients]

AIM

To evaluate the contribution of multiparametric MRI (MRI) and targeted biopsies (TB) in the selection and follow-up of patients under active surveillance (AS).

METHODS

A single-center, retrospective cohort study on 131 patients in AS, with following criteria:≤cT2 stage, PSA≤15ng/mL, Gleason score≤6,≤3 positive biopsies and maximum tumor length≤5mm. Patients' selection and follow-up was performed by the combination of systemic biopsies (SB) and mpMRI±TB. Reclassification was defined by a Gleason score>6 and/or a maximum tumor length>5mm.

RESULTS

Overall, 29 patients (22.1 %) were reclassified. Reclassification free survival rate was 93 % and 70 % at 1 year and 4 years respectively. Reclassification independent risk factors were: PSA density>0.15ng/mL/cm³ (RR=2.75), PSA doubling time<3 years (RR=9.28), suspicious lesion on MRI diagnosis (RR=2.79) and occurrence of MRI progression during follow-up (RR=2). Sensitivity, specificity, PPV and NPV of MRI to assess progression for reclassification were 61 %, 69 %, 45 % and 81 %, respectively.

CONCLUSION

For patients under AS, mpMRI decreases reclassification rates over time through better initial detection of significant cancers. Its high NPV makes it an efficient monitoring tool to distinguish patients with low risk of reclassification.

LEVEL OF EVIDENCE

4.

Multiparametric Magnetic-Resonance to Confirm Eligibility to an Active Surveillance Program for Low-Risk Prostate Cancer: Intermediate Time Results of a Third Referral High Volume Centre Active Surveillance Protocol

BACKGROUND

To evaluate the role of confirmatory multiparametric magnetic resonance imaging (mpMRI) of the prostate at the time of Active Surveillance (AS) enrollment to reduce disease misclassification.

MATERIALS

From 2012 to 2016, 383 patients with low-risk disease respecting Prostate Cancer Research International AS criteria underwent confirmatory 1.5-T mpMRI. AS was proposed to patients with Prostate Imaging and Report and Data System (PI-RADS) score ≤3 and no extraprostatic extension (EPE), whereas patients with PI-RADS score ≥4 and/or EPE were treated actively. Kaplan-Meier analyses quantified progression-free survival (PFS) in patients enrolled in the AS program. Logistic regression analyses tested the association between confirmatory mpMRI and clinically significant prostate cancer (csPCa) at radical prostatectomy (RP). Diagnostic performance of mpMRI was calculated in patients submitted to immediate RP.

RESULTS

PFS rate was 99, 90 and 86% at 1, 2 and 3 years respectively. At multivariable analysis, PI-RADS 3, PI-RADS 4, PI-RADS 5 and EPE increased the probability of having csPCa at immediate RP (PI-RADS 3 [OR] 1.2, p = 0.26; PI-RADS 4 [OR] 5.1, p = 0.02; PI-RADS 5 [OR] 6.7; p = 0.009; EPE [OR] 11.8, p < 0.001). Confirmatory mpMRI showed sensibility, specificity, positive predictive value and negative predictive value of 85, 55, 68 and 76% respectively.

CONCLUSIONS

MpMRI at the time of AS enrollment reduces the misclassification rate of csPCa. We suggest to perform target biopsies in patients with PI-RADS score 3 and 4 lesions.

Active surveillance review: contemporary selection criteria, follow-up, compliance and outcomes

The primary goal of active surveillance (AS) is to prevent overtreatment by selecting patients with low-risk prostate cancer (PCa) and closely monitoring them so that definitive treatment can be offered when needed. With the increasing popularity of AS as a management strategy for men with localized PCa, it is important to understand all the contemporary guidelines and criteria that exist for AS and the differences among them. No single optimal management strategy for clinically localized, early-stage disease has been universally accepted. The implementation of AS varies widely between institutions, from inclusion criteria to follow-up protocols, with the most notable differences seen in maximum accepted Gleason score, T-stage and prostate-specific antigen (PSA) parameters. The objectives of this review were to systematically summarize the current literature on AS strategy, present an overview of the various published guidelines and criteria that are used for AS at several major institutions as well as discuss goals and trade-offs of the various criteria. A comprehensive search of the PubMed and Embase databases from 1990 to 2017 was performed to identify studies pertaining to AS criteria and trends. Trends in AS uptake and use in Canada, USA and Europe were reviewed to demonstrate the current trends and outcomes of AS to offer greater insight into the differences, nature and efficacy of various AS protocols. AS is a compelling antidote to the current PCa overtreatment phenomena; however, when considering patients for AS it is important to understand the differences between protocols, and review published results to appreciate the impact on follow-up.

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.

Targeted Prostate Biopsy in the Era of Active Surveillance

Targeted prostate biopsy using magnetic resonance imaging (MRI) guidance is improving the accuracy of prostate cancer (CaP) diagnosis. This new biopsy technology is especially important for men undergoing active surveillance, improving patient selection for enrollment and enabling precise longitudinal monitoring. Magnetic resonance imaging/ultrasound fusion biopsy allows for 3 functions not previously possible with US-guided biopsy: targeting of suspicious regions, template-mapping for systematic sampling, and tracking of cancer foci over time. This article reviews the evolving role of the new biopsy methods in active surveillance, including the UCLA Active Surveillance pathway, which has incorporated magnetic resonance imaging/ultrasound fusion biopsy from program inception as a possible model.

MR Imaging for Prostate Cancer Screening and Active Surveillance

The current prostate cancer management paradigm has been criticized in recent years for contributing to the overdiagnosis and overtreatment of the disease. Active surveillance is an avenue by which to reduce overtreatment, but patient selection and monitoring remain a challenge. The use of prostate MR imaging has been growing in recent years and has been incorporated into prostate cancer screening and patient selection and monitoring for active surveillance. This review article discusses the current evidence for the use of MR imaging in each of those settings.

Prostate Cancer Imaging and Biomarkers Guiding Safe Selection of Active Surveillance

Background

Active surveillance (AS) is a widely adopted strategy to monitor men with low-risk, localized prostate cancer (PCa). Current AS inclusion criteria may misclassify as many as one in four patients. The advent of multiparametric magnetic resonance imaging (mpMRI) and novel PCa biomarkers may offer improved risk stratification. We performed a review of recently published literature to characterize emerging evidence in support of these novel modalities.

Methods

An English literature search was conducted on PubMed for available original investigations on localized PCa, AS, imaging, and biomarkers published within the past 3 years. Our Boolean criteria included the following terms: PCa, AS, imaging, biomarker, genetic, genomic, prospective, retrospective, and comparative. The bibliographies and diagnostic modalities of the identified studies were used to expand our search.

Results

Our review identified 222 original studies. Our expanded search yielded 244 studies. Among these, 70 met our inclusion criteria. Evidence suggests mpMRI offers improved detection of clinically significant PCa, and MRI-fusion technology enhances the sensitivity of surveillance biopsies. Multiple studies demonstrate the promise of commercially available screening assays for prediction of AS failure, and several novel biomarkers show promise in this setting.

Conclusion

In the era of AS for men with low-risk PCa, improved strategies for proper stratification are needed. mpMRI has dramatically enhanced the detection of clinically significant PCa. The advent of novel biomarkers for prediction of aggressive disease and AS failure has shown some initial promise, but further validation is warranted.

The role of whole-lesion apparent diffusion coefficient analysis for predicting outcomes of prostate cancer patients on active surveillance

PURPOSE

To explore the role of whole-lesion apparent diffusion coefficient (ADC) analysis for predicting outcomes in prostate cancer patients on active surveillance.

METHODS

This study included 72 prostate cancer patients who underwent MRI-ultrasound fusion-targeted biopsy at the initiation of active surveillance, had a visible MRI lesion in the region of tumor on biopsy, and underwent 3T baseline and follow-up MRI examinations separated by at least one year. Thirty of the patients also underwent an additional MRI-ultrasound fusion-targeted biopsy after the follow-up MRI. Whole-lesion ADC metrics and lesion volumes were computed from 3D whole-lesion volumes-of-interest placed on lesions on the baseline and follow-up ADC maps. The percent change in lesion volume on the ADC map between the serial examinations was computed. Statistical analysis included unpaired t tests, ROC analysis, and Fisher's exact test.

RESULTS

Baseline mean ADC, ADC_{0-10th-percentile}, ADC_{10-25th-percentile}, and ADC_{25-50th-percentile} were all significantly lower in lesions exhibiting ≥50% growth on the ADC map compared with remaining lesions (all P ≤ 0.007), with strongest difference between lesions with and without ≥50% growth observed for ADC_{0-10th-percentile} (585 ± 308 vs. 911 ± 336; P = 0.001). ADC_{0-10th-percentile} achieved highest performance for predicting ≥50% growth (AUC = 0.754). Mean percent change in tumor volume on the ADC map was 62.3% ± 26.9% in patients with GS ≥ 3 + 4 on follow-up biopsy compared with 3.6% ± 64.6% in remaining patients (P = 0.050).

CONCLUSION

Our preliminary results suggest a role for 3D whole-lesion ADC analysis in prostate cancer active surveillance.

Reclassification Rates of Patients Eligible for Active Surveillance After the Addition of Magnetic Resonance Imaging-Ultrasound Fusion Biopsy: An Analysis of 7 Widely Used Eligibility Criteria

OBJECTIVES

To evaluate the impact of adding magnetic resonance imaging-ultrasound (MRI-US) fusion biopsy cores to standard 12-core biopsy in selecting men for active surveillance (AS).

MATERIALS AND METHODS

Among men undergoing a fusion biopsy for evaluation of prostate cancer, we selected men who were eligible for at least 1 of 7 different AS criteria based on the standard biopsy alone. We assessed each patient's eligibility for each AS criterion with and without the inclusion of fusion biopsy cores. The primary end point was the proportion of men who were initially eligible for AS but became ineligible after addition of the fusion biopsy cores.

RESULTS

A total of 100 men were eligible for at least 1 AS criterion. After addition of fusion biopsy cores, the proportion of men who became ineligible for AS varied from 10.3% to 40.7%. Criteria that incorporated an absolute maximum number of cores positive had the highest rates of ineligibility. Using a percentage of cores positive helped to reduce the number of patients who would have been excluded. Combining the targeted biopsy cores into one, or taking the single core with the highest grade or volume did not appear to reduce the proportion of men who became ineligible.

CONCLUSIONS

The addition of fusion biopsy to standard 12-core biopsy significantly increased the number of men who became ineligible for AS. Using the percent of cores positive, instead of an absolute number, allowed fewer exclusions. AS criteria may need to be updated to prevent the unnecessary exclusion of men due to an oversampling of low-risk disease.

Role of prostate magnetic resonance imaging in active surveillance

Active surveillance (AS) has emerged as a beneficial strategy for management of low risk prostate cancer (PCa) and prevention of overtreatment of indolent disease. However, selection of patients for AS using traditional 12-core transrectal prostate biopsy is prone to sampling error and presents a challenge for accurate risk stratification. In fact, around a third of men are upgraded on repeat biopsy which disqualifies them as appropriate AS candidates. This uncertainty affects adoption of AS among patients and physicians, leading to current AS protocols involving repetitive prostate biopsies and unclear triggers for progression to definitive treatment. Prostate magnetic resonance imaging (MRI) has the potential to overcome some of these limitations through localization of significant tumors in the prostate. In conjunction with MRI-targeted prostate biopsy, improved sampling and detection of clinically significant PCa can help streamline the process of selecting suitable men for AS and early exclusion of men who require definitive treatment. MRI can also help minimize the invasive nature of monitoring for disease progression while on AS. Men with stable MRI findings have high negative predictive value for Gleason upgrade on subsequently biopsy, suggesting that men may potentially be monitored by serial MRI examinations with biopsy reserved for significant changes on imaging. Targeted biopsy on AS also allows for specific sampling of concerning lesions, although further data is necessary to evaluate the relative contribution of systematic and targeted biopsy in detecting the 25-30% of men who progress on AS. Further research is also warranted to better understand the nature of clinically significant cancers that are missed on MRI and why certain men have progression of disease that is not visible on prostate MRI. Consensus is also needed over what constitutes progression on MRI, when prostate biopsy can be safely avoided, and how to best utilize this additional information in current AS protocols. Despite these challenges, prostate MRI, either alone or in conjunction with MRI-targeted prostate biopsy, has the potential to significantly improve our current AS paradigm and rates of AS adoption among patients moving forward.

Multi-parametric magnetic resonance imaging as a management decision tool

The ability to image the prostate accurately and better characterize cancerous lesions makes multiparametric magnetic resonance imaging (mpMRI) an invaluable tool to improve management of localized prostate cancer (PCa). Improved risk stratification is warranted given the evidence of significant overtreatment of indolent PCa. mpMRI can more accurately rule out clinically significant PCa in men deciding between surveillance and definitive treatment to reduce overtreatment. mpMRI improves detection of clinically significant PCa, which helps minimize sampling error, a major limitation of the traditional diagnostic paradigm. Aside from helping determine candidacy for initial surveillance vs. treatment, mpMRI is a useful tool for following men on active surveillance (AS) with the potential to reduce the need for serial biopsies. When definitive treatment is warranted, mpMRI can be used to determine the local extent of disease. This provides information that is useful in the treatment decision, counseling about outcomes, and surgical planning. While mpMRI is a significant step forward in PCa management, it is necessary to understand its limitations. mpMRI and MRI-guided fusion biopsy techniques still do not detect all clinically significant tumors. The utility of current mpMRI techniques is limited by the multifocal nature of PCa with poor detection of non-index lesions, inaccurate estimation of tumor size and geometry, and the need for interpretation by specialized radiologists. The role of mpMRI will continue to expand as improvements in technology and experience help overcome these limitations.

Biomarker, Molecular, and Technologic Advances in Urologic Pathology, Oncology, and Imaging

Urologic pathology is evolving rapidly. Emerging trends include the expanded diagnostic utility of biomarkers and molecular testing, as well as adapting to the plethora of technical advances occurring in genitourinary oncology, surgical practice, and imaging. We illustrate those trends by highlighting our approach to the diagnostic workup of a few selected disease entities that pathologists may encounter, including newly recognized subtypes of renal cell carcinoma, pheochromocytoma, and prostate cancer, some of which harbor a distinctive chromosomal translocation, gene loss, or mutation. We illustrate applications of immunohistochemistry for differential diagnosis of needle core renal biopsies, intraductal carcinoma of the prostate, and amyloidosis and cite encouraging results from early studies using targeted gene expression panels to predict recurrence after prostate cancer surgery. At our institution, pathologists are working closely with urologic surgeons and interventional radiologists to explore the use of intraoperative frozen sections for margins and nerve sparing during robotic prostatectomy, to pioneer minimally invasive videoscopic inguinal lymphadenectomy, and to refine image-guided needle core biopsies and cryotherapy of prostate cancer as well as blue-light/fluorescence cystoscopy. This collaborative, multidisciplinary approach enhances clinical management and research, and optimizes the care of patients with urologic disorders.

The Emerging Role of MRI in Prostate Cancer Active Surveillance and Ongoing Challenges

OBJECTIVE

Active surveillance (AS) has emerged as a management strategy for preventing overtreatment of indolent prostate cancer. Selection of patients for AS has traditionally proved challenging and resulted in 20-30% misclassification rates. MRI has potential to help overcome this limitation, broaden selection criteria to increase recruitment, and minimize the invasive nature of AS follow-up.

CONCLUSION

The main issues surrounding MRI and AS are the heterogeneity of inclusion criteria, the definition of significant disease, and agreement about what constitutes radiologic progression. Prospective cohorts with MRI at enrollment and long-term follow-up are required to further address these issues.

MR Spectroscopy in Prostate Cancer: New Algorithms to Optimize Metabolite Quantification

Prostate cancer (PCa) is the most common non-cutaneous cancer in male subjects and the second leading cause of cancer-related death in developed countries. The necessity of a non-invasive technique for the diagnosis of PCa in early stage has grown through years. Proton magnetic resonance spectroscopy (1H-MRS) and proton magnetic resonance spectroscopy imaging (1H-MRSI) are advanced magnetic resonance techniques that can mark the presence of metabolites such as citrate, choline, creatine and polyamines in a selected voxel, or in an array of voxels (in MRSI) inside prostatic tissue. Abundance or lack of these metabolites can discriminate between pathological and healthy tissue. Although the use of magnetic resonance spectroscopy (MRS) is well established in brain and liver with dedicated software for spectral analysis, quantification of metabolites in prostate can be very difficult to achieve, due to poor signal to noise ratio and strong J-coupling of the citrate. The aim of this work is to develop a software prototype for automatic quantification of citrate, choline and creatine in prostate. Its core is an original fitting routine that makes use of a fixed step gradient descent minimization algorithm (FSGD) and MRS simulations developed with the GAMMA libraries in C++. The accurate simulation of the citrate spin systems allows to predict the correct J-modulation under different NMR sequences and under different coupling parameters. The accuracy of the quantifications was tested on measurements performed on a Philips Ingenia 3T scanner using homemade phantoms. Some acquisitions in healthy volunteers have been also carried out to test the software performance in vivo.

Current practice and access to prostate MR imaging in France

PURPOSE

To obtain an overview of the degree of discrepancy between current clinical practice of prostate magnetic resonance imaging (MRI) in France and recommendations.

MATERIALS AND METHODS

A brief survey was sent to 1229 members of the French society of urology in order to identify their indications of prostate MRI and its impact on patient management. The urologists were asked to answer several questions regarding age, practice modality, prostate MRI examinations (technique, indication before first biopsy, second biopsy, cancer staging, active surveillance, recurrence, focal therapy) and quality of reports.

RESULTS

A total of 445 responses were received (participation rate of 36%). The mean delay for obtaining an appointment for prostate MRI ranged between 15-30 days in 54%. Fifty-four percent of MRI reports contained a PIRADS score and 23% a Likert score. The indications of multiparametric-MRI were tumor detection/location prior to repeat biopsy (90%), cancer staging (85%), management of patients under active surveillance (85%), selection of candidates to focal therapy (63%), tumor detection/location in biopsy naïve patients (53%), detection of local recurrence after radical (51%). Only 119 urologists (28.6%) had access to image fusion (MRI and transrectal ultrasound) and 351 (85.4%) used cognitive fusion. Mostly, targeted biopsies are done by urologists alone (nearly 80%), a very few are done by radiologists (8%) or by the two of them in collaboration (12%).

CONCLUSION

The majority of urologists consider that prostate MRI is essential for the management of patients with prostate cancer. Practices are ahead of recommendations particularly before the first biopsy and in active surveillance.