Prostate cancer: in-bore magnetic resonance guided biopsies at active surveillance inclusion improve selection of patients for active treatment

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.

Confirmatory multiparametric magnetic resonance imaging at recruitment confers prolonged stay in active surveillance and decreases the rate of upgrading at follow-up

BACKGROUND

To understand the value of multiparametric magnetic resonance imaging (mpMRI) and targeted biopsies at recruitment on active surveillance (AS) outcomes.

MATERIALS AND METHODS

This retrospective single-center study enrolled two cohorts of 206 and 310 patients in AS. The latter group was submitted to mpMRI and targeted biopsies at recruitment. Kaplan-meier curves quantified progression-free survival (PFS) and Bioptic-PFS (B-PFS: no upgrading or >3 positive cores) in the two cohorts. Cox-regression analyses tested independent predictors of PFS and B-PFS. In patients submitted to radical prostatectomy (RP) after AS, significant cancer (csPCa) was defined as: GS ≥ 4 + 3 and/or pT ≥ 3a and/or pN+ . Logistic-regression analyses predicted csPCa at RP.

RESULTS AND LIMITATIONS

Median time follow-up and median time of persistence in AS were 46 (24-70) and 36 (23-58) months, respectively. Patients submitted to mpMRI at AS begin, showed greater PFS at 1- (98% vs. 91%), 3- (80% vs. 57%), and 5-years (70% vs. 35%) follow-up, respectively (all p < 0.01). At Cox-regression analysis only confirmatory mpMRI± targeted biopsy (HR: 0.3; 95% CI 0.2-0.5; p < 0.01) at AS begin was an independent predictor of PFS. Globally, 50 (16%) vs. 128 (62%) and 26 (8.5%) vs. 64 (31%) [all p < 0.01] men in the two groups experienced any-cause and bioptic AS discontinuation, respectively. Patients submitted to confirmatory mpMRI experienced greater 1-(98% vs. 93%), 3-(90% vs. 75%), and 5-years (83% vs. 56%) B-PFS, respectively (all p < 0.01). At Cox-regression analysis, mpMRI±-targeted biopsy at AS begin was associated with B-PFS (HR: 0.3; 95% CI 0.2-0.6; p < 0.01). No differences were recorded in csPCa rates between the two groups (22% vs. 28%; p = 0.47). Limitations of the study are the single-center retrospective nature and the absence of long-term follow-up.

CONCLUSIONS

Confirmatory mpMRI±-targeted biopsies are associated with higher PFS and B-PFS during AS. However, a non-negligible percentage of patients experience csPCa after switching to active treatment.

Changes in risk-group stratification of patients undergoing radical prostatectomy at the Southern Alberta Institute of Urology over time

Introduction

Prostate cancer is the most common cancer among men, but overall mortality rates remain low, due to the preponderance of low-risk disease. Over the last decade, there has been a shift toward more conservative management in low-risk prostate cancer, in order to minimize unnecessary intervention. This study aimed to evaluate the number of low-risk radical prostatectomies (RPs) being performed at the Southern Alberta Institute of Urology over a 10-year period.

Methods

We retrospectively reviewed all patients who underwent RP from 2005 to 2014 at our institution. Patients were stratified by D’Amico risk classification and grade group based on 12-core transrectal ultrasound–guided biopsy (TRUS-bx) results. RP findings are reported from February 2005 to October 2014 to describe concordance between TRUS-bx and RPs. Basic descriptive analyses were used for this study.

Results

Over the study period, 2,310 RPs were performed in our institution. Overall, 35.2% of these were performed on men with low-risk prostate cancer. From 2005 to 2014, the proportion of RPs performed for low-risk prostate cancer dropped from 54.0% to 8.9%, and 49.8% of patients who underwent RP for low-risk disease experienced pathologic upgrading, though only 3.8% were upgraded to grade group 3 or greater. Other adverse pathological findings were uniformly low among the low-risk group.

Conclusion

The proportion of patients undergoing RP at our center for low-risk prostate cancer decreased significantly over the 10 years evaluated in this study, reflecting current global trends toward active surveillance in the management of low-risk prostate cancer.

Quantitative Tumor Perfusion Imaging with 82Rb PET/CT in Prostate Cancer: Analytic and Clinical Validation

The aim of this work was to evaluate ⁸²Rb PET/CT as a diagnostic tool for quantitative tumor blood flow (TBF) imaging in prostate cancer (PCa). Study 1 was performed to evaluate ⁸²Rb as a marker of TBF, using ¹⁵O-H₂O PET as a reference method. Study 2 investigated the ability of ⁸²Rb uptake measurements to differentiate between PCa and normal prostate. Methods: Study 1: 9 PCa patients scheduled for radical prostatectomy were included. Prostate multiparametric MRI and both cardiac and pelvic ¹⁵O-H₂O PET and ⁸²Rb PET were performed. PET findings were compared with postprostatectomy Gleason grade group (GGG). Study 2: 15 primary high-risk PCa patients and 12 controls without known prostate disease were included in a clinical drug trial (EudraCT 2016-003185-26). ⁶⁸Ga-prostate-specific membrane antigen PET/CT scans of PCa patients were available. Pelvic ⁸²Rb PET was performed. Results: Study 1: both ⁸²Rb K ₁ and ⁸²Rb SUVs correlated strongly with ¹⁵O-H₂O TBF (ρ = 0.95, P < 0.001, and ρ = 0.77, P = 0.015, respectively). ⁸²Rb SUV and K ₁ were linearly correlated (r = 0.92, P = 0.001). ⁸²Rb SUV correlated with postprostatectomy GGG (ρ = 0.70, P = 0.03). Study 2: ⁸²Rb SUV in PCa (3.19 ± 0.48) was significantly higher than prostate ⁸²Rb SUV in healthy controls (1.68 ± 0.37) (P < 0.001), with no overlap between groups. Conclusion: Study 1 shows that ⁸²Rb PET/CT can be used for TBF quantification and that TBF can be estimated by simple SUV and suggests that ⁸²Rb SUV is associated with postprostatectomy GGG and, hence, cancer aggressiveness. Study 2 shows that ⁸²Rb uptake is significantly higher in PCa than in normal prostate tissue with no overlap between cohorts, confirming the primary hypothesis of the clinical trial. Consequently, ⁸²Rb PET/CT may have potential as a noninvasive tool for evaluation of tumor aggressiveness and monitoring in nonmetastatic PCa.

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.

Review of Gallium-68 PSMA PET/CT Imaging in the Management of Prostate Cancer

Over 90% of prostate cancers over-express prostate specific membrane antigen (PSMA) and these tumor cells may be accurately targeted for diagnosis by 68Ga-PSMA-positron emission tomography/computed tomography (68Ga-PSMA-PET/CT) imaging. This novel molecular imaging modality appears clinically to have superseded CT, and appears superior to MR imaging, for the detection of metastatic disease. 68Ga-PSMA PET/CT has the ability to reliably stage prostate cancer at presentation and can help inform an optimal treatment approach. Novel diagnostic applications of 68Ga-PSMA PET/CT include guiding biopsy to improve sampling accuracy, and guiding surgery and radiotherapy. In addition to facilitating the management of metastatic castrate resistant prostate cancer (mCRPC), 68Ga-PSMA can select patients who may benefit from targeted systemic radionuclide therapy. 68Ga-PSMA is the diagnostic positron-emitting theranostic pair with the beta emitter Lutetium-177 PSMA (177Lu-PSMA) and alpha-emitter Actinium-225 PSMA (225Ac-PSMA) which can both be used to treat PSMA-avid metastases of prostate cancer in the molecular tumor-targeted approach of theranostic nuclear oncology.

Multi-parametric magnetic resonance imaging monitoring patients in active surveillance for prostate cancer: a prospective cohort study

OBJECTIVES

To evaluate the use of multi-parametric magnetic resonance imaging (mpMRI) and mpMRI guided biopsies (MRGB) for monitoring an active surveillance (AS) prostate cancer cohort.

MATERIALS AND METHODS

One year after initial diagnostic TRUS guided biopsy (TRUS-bx), baseline mpMRI, and enrolment in an AS program patients underwent a one year follow-up comprising the usual TRUS-bx and an mpMRI. Prostate MRI lesions were scored on the five-point PIRADS scale version 2. In cases without TRUS-bx progression, patients with PIRADS 4 or 5 lesions were scheduled for MRGB. Progression in TRUS-bx was defined as Gleason score (Gs) up-grades, >3 tumor positive cores or a maximal cancer core length (MCCL) > 50%. In MRGB, Gs upgrade or a MCCL ≥6 mm Gs 3 + 3 lesions were considered to reflect progression. PSA increase or progression in clinical T-classification alone was not considered clinical progression.

RESULTS

50 patients were included in the study. In total 10 (20%) patients had per definition progression at one year follow-up. Seven patients (7/50 = 14%) had clinical progression based on TRUS-bx. mpMRI identified seven newly emerged PIRADS 4 lesions. Three patients with PIRADS 4 lesions had no sign of TRUS-bx progression, while MRGB revealed significant cancer (Gs 7 (3 + 4) and Gs 8 (3 + 5)). Consequently, seven patients underwent definitive treatment. Of these, six and four had a progression on MRI and TRUS-bx, respectively.

CONCLUSIONS

Our study suggests that mpMRI is at least equal to TRUS-bx in detecting progression at one year follow-up in prostate cancer patients undergoing active surveillance.