Understanding Spatial Correlation Between Multiparametric MRI Performance and Prostate Cancer

BACKGROUND

Multiparametric MRI (mpMRI) has shown a substantial impact on prostate cancer (PCa) diagnosis. However, the understanding of the spatial correlation between mpMRI performance and PCa location is still limited.

PURPOSE

To investigate the association between mpMRI performance and tumor spatial location within the prostate using a prostate sector map, described by Prostate Imaging Reporting and Data System (PI-RADS) v2.1.

STUDY TYPE

Retrospective.

SUBJECTS

One thousand one hundred forty-three men who underwent mpMRI before radical prostatectomy between 2010 and 2022.

FIELD STRENGTH/SEQUENCE

3.0 T. T2-weighted turbo spin-echo, a single-shot spin-echo EPI sequence for diffusion-weighted imaging, and a gradient echo sequence for dynamic contrast-enhanced MRI sequences.

ASSESSMENT

Integrated relative cancer prevalence (rCP), detection rate (DR), and positive predictive value (PPV) maps corresponding to the prostate sector map for PCa lesions were created. The relationship between tumor location and its detection/missing by radiologists on mpMRI compared to WMHP as a reference standard was investigated.

STATISTICAL TESTS

A weighted chi-square test was performed to examine the statistical differences for rCP, DR, and PPV of the aggregated sectors within the zone, anterior/posterior, left/right prostate, and different levels of the prostate with a statistically significant level of 0.05.

RESULTS

A total of 1665 PCa lesions were identified in 1143 patients, and from those 1060 lesions were clinically significant (cs)PCa tumors (any Gleason score [GS] ≥7). Our sector-based analysis utilizing weighted chi-square tests suggested that the left posterior part of PZ had a high likelihood of missing csPCa lesions at a DR of 67.0%. Aggregated sector analysis indicated that the anterior or apex locations in PZ had the significantly lowest csPCa detection at 67.3% and 71.5%, respectively.

DATA CONCLUSION

Spatial characteristics of the per-lesion-based mpMRI performance for diagnosis of PCa were studied. Our results demonstrated that there is a spatial correlation between mpMRI performance and locations of PCa on the prostate.

EVIDENCE LEVEL

4 TECHNICAL EFFICACY: Stage 2.

Clinical experience with active surveillance protocol using regular magnetic resonance imaging instead of regular repeat biopsy for monitoring: A study at a high-volume center in Korea

Background

Here, we report the experience of a multiparameter magnetic resonance imaging (MRI)–based active surveillance (AS) protocol that did not include performing a repeat biopsy after the diagnosis of prostate cancer by prostate biopsy or transurethral resection of prostate.

Methods

From January 2010 to December 2017, we reviewed 193 patients with newly diagnosed prostate cancer who were eligible for AS. The patients were divided into AS group (n = 122) and definitive treatment group (n = 71) based on initial treatment. Disease progression was defined as a remarkable change in MRI findings. To confirm the stability of protocol, we compared the clinicopathological characteristics of patients who initially underwent radical prostatectomy (RP) (n = 58) and RP after termination of AS (n = 20).

Results

Among patients who initially selected AS (median adherence duration = 31.4 months), 70 (57.3%) subsequently changed their treatment options. Disease progression (n = 30) was the main cause for termination. No significant differences were found in the clinicopathologic characteristics at initial diagnosis and pathologic outcomes between patients who initially underwent RP and those who chose RP after termination of AS. In a comparative analysis of diagnostic methods, the patients with incidental prostate cancer by transurethral resection of prostate had higher age, lower prostate-specific antigen level and density, as well as longer AS adherence duration and follow-up duration compared with those diagnosed by prostate biopsy.

Conclusions

Our AS monitoring protocol, which depends on MRI instead of regular repeat biopsy, was feasible. Patients with incidental prostate cancer continued AS more compared with patients diagnosed by prostate biopsy.

Current Status of MRI and PET in the NCCN Guidelines for Prostate Cancer

Prostate cancer (PCa) represents a significant source of morbidity and mortality for men in the United States, with approximately 1 in 9 being diagnosed with PCa in their lifetime. The role of imaging in the evaluation of men with PCa has evolved and currently plays a central role in diagnosis, treatment planning, and evaluation of recurrence. Appropriate use of multiparametric MRI (mpMRI) and MRI-guided transrectal ultrasound (MR-TRUS) biopsy increases the detection of clinically significant PCa while decreasing the detection of clinically insignificant PCa. This process may help patients with clinically insignificant PCa avoid the adverse effects of unnecessary therapy. In the setting of a known PCa, patients with low-grade disease can be observed using active surveillance, which often includes a combination of prostate-specific antigen (PSA) testing, serial mpMRI, and, if indicated, follow-up systematic and targeted TRUS-guided tissue sampling. mpMRI can provide important information in the posttreatment setting, but PET/CT is creating a paradigm shift in imaging standards for patients with locally recurrent and metastatic PCa. This article examines the strengths and limitations of mpMRI for initial PCa diagnosis, active surveillance, recurrent disease evaluation, and image-guided biopsies, and the use of PET/CT imaging in men with recurrent PCa. The goal of this review is to provide a rational basis for current NCCN Clinical Practice Guidelines in Oncology for PCa as they pertain to the use of these advanced imaging modalities.

The significance of the visible tumor on preoperative magnetic resonance imaging in localized prostate cancer

Objectives

We investigated the relationship between tumor characteristics and visible tumors on magnetic resonance imaging (MRI) and examined the prognosis of tumor detection on MRI compared with no tumor detection in localized prostate cancer.

Materials and methods

We reviewed 214 patients with pT2N0M0 prostate cancer who underwent radical prostatectomy between January 2009 and December 2016. All the patients underwent MRI preoperatively. The patients were divided into 2 groups postoperatively: no visible tumor on the MRI group (n = 96, 44.9%) and visible tumor on the MRI group (n = 118, 55.1%). The visible tumor was defined as Prostate Imaging Reporting and Data System, version 2 Grade ≥ 3 on MRI. Age, prostate-specific antigen, prostate volume, positive surgical margin (PSM), lymphovascular invasion, and biochemical recurrence (BCR) were compared between the 2 groups. We also assessed the relationship between visible tumors on MRI and oncologic characteristics.

Results

The visible tumor on the MRI group showed a higher Gleason score ≥4 + 3 [45.8% versus (vs.) 17.7%], high frequency of postoperative PSMs (28.8% vs. 16.7%), and higher BCR rate (17.8% vs. 7.3%) than the no visible tumor on the MRI group. The Kaplan–Meier analysis for BCR-free survival also showed a significant difference (P = 0.006). In multivariate Cox regression analysis, the detection of tumors on MRI was associated with a higher BCR risk [hazard ratio: 3.35; 95% confidence interval (CI): 1.36-8.27; P = 0.009]. We found a positive association between visible tumors on MRI and primary Gleason pattern of ≥4 (odds ratio: 4.31; 95% CI: 2.21–8.40; P < 0.001).

Conclusions

In localized prostate cancer, BCR was significantly more frequent when the tumor was detected on MRI, and a visible tumor on MRI was associated with the Gleason score. Therefore, attention should be paid to the possibility of high-grade prostate cancer when a tumor is detected on MRI before radical prostatectomy, and active follow-up may be needed postoperatively.

Automated segmentation of prostate zonal anatomy on T2-weighted (T2W) and apparent diffusion coefficient (ADC) map MR images using U-Nets

PURPOSE

Accurate regional segmentation of the prostate boundaries on magnetic resonance (MR) images is a fundamental requirement before automated prostate cancer diagnosis can be achieved. In this paper, we describe a novel methodology to segment prostate whole gland (WG), central gland (CG), and peripheral zone (PZ), where PZ + CG = WG, from T2W and apparent diffusion coefficient (ADC) map prostate MR images.

METHODS

We designed two similar models each made up of two U-Nets to delineate the WG, CG, and PZ from T2W and ADC map MR images, separately. The U-Net, which is a modified version of a fully convolutional neural network, includes contracting and expanding paths with convolutional, pooling, and upsampling layers. Pooling and upsampling layers help to capture and localize image features with a high spatial consistency. We used a dataset consisting of 225 patients (combining 153 and 72 patients with and without clinically significant prostate cancer) imaged with multiparametric MRI at 3 Tesla.

RESULTS AND CONCLUSION

Our proposed model for prostate zonal segmentation from T2W was trained and tested using 1154 and 1587 slices of 100 and 125 patients, respectively. Median of Dice similarity coefficient (DSC) on test dataset for prostate WG, CG, and PZ were 95.33 ± 7.77%, 93.75 ± 8.91%, and 86.78 ± 3.72%, respectively. Designed model for regional prostate delineation from ADC map images was trained and validated using 812 and 917 slices from 100 and 125 patients. This model yielded a median DSC of 92.09 ± 8.89%, 89.89 ± 10.69%, and 86.1 ± 9.56% for prostate WG, CG, and PZ on test samples, respectively. Further investigation indicated that the proposed algorithm reported high DSC for prostate WG segmentation from both T2W and ADC map MR images irrespective of WG size. In addition, segmentation accuracy in terms of DSC does not significantly vary among patients with or without significant tumors.

SIGNIFICANCE

We describe a method for automated prostate zonal segmentation using T2W and ADC map MR images independent of prostate size and the presence or absence of tumor. Our results are important in terms of clinical perspective as fully automated methods for ADC map images, which are considered as one of the most important sequences for prostate cancer detection in the PZ and CG, have not been reported previously.

The role of Prostate Imaging Reporting and Data System score in Gleason 3 + 3 active surveillance candidates enrollment: a diagnostic meta-analysis

BACKGROUND

The contemporary active surveillance (AS) criteria may result in an unsatisfactory misclassification rate, which may delay curative treatment for prostate cancer patients. The magnetic resonance imaging (MRI), not included in any AS criteria, provides useful information for prostate cancer diagnosis. Our goal is to evaluate the diagnostic performance of Prostate Imaging Reporting and Data Systems (PI-RADS) score, a standardized MRI reporting system, in AS candidates enrollment.

METHODS

We searched Cochrane CENTRAL, PubMed, and Embase for pertinent studies through June 2018. The standard methods recommended for meta-analyses of diagnostic evaluation were employed. We draw the summary receiver operating characteristic (SROC) curve. Meta-regression analysis was performed to evaluate the effects of confounding factors.

RESULTS

From the resulting 168 studies, 5 provided the diagnostic data on PI-RADS score and pathological results; 834 patients were included. All AS candidates in these studies were defined by Prostate Cancer Research International: Active Surveillance (PRIAS) criterion. The pooled estimates of PI-RADS 4 or 5 on adverse pathological features at radical prostatectomy (RP) among AS candidates were: sensitivity, 0.77 (95% confidence interval (CI), 0.71-0.82); specificity, 0.63 (95% CI, 0.55-0.71); positive predictive value, 0.72 (95% CI, 0.64-0.79); negative predictive value, 0.68 (95% CI, 0.63-0.73); and diagnostic odds ratio, 6 (95% CI, 4-8). The SROC curve was positioned toward the desired upper left corner of the curve, the area under the curve was 0.77 (95% CI, 0.73-0.80). The P-value for heterogeneity was <0.01. The pathological outcomes and endorectal coils contributed to the heterogeneity of sensitivity. The evidences supporting the advantage of PI-RADS v2 over v1 were not sufficient yet.

CONCLUSION

AS candidates with PI-RADS 4 or 5 may be unsuitable for AS even though they fulfill current AS criteria. Those with PI-RADS 3 or less indicated relative safety for AS enrollment.

Quantitation of hypoechoic lesions for the prediction and Gleason grading of prostate cancer: a prospective study

PURPOSE

Hypoechoic lesions are not included as indicators for prostate biopsy. To discriminate the features of hypoechoic lesions, we investigated the ultrasonographic characteristics of hypoechoic lesions using numerical analysis in image. In addition, we evaluated previously suggested subjective parameters on hypoechoic lesion.

METHODS

We performed one-core targeted biopsy (TBx) for each hypoechoic lesion in up to two lesions in each patient before the 12-core systemic biopsy was obtained between July 2015 and May 2016. Image analysis data were analyzed using grayscale values and Hounsfield units (HU) to measure heterogeneity. Subjective evaluation of hypoechoic lesions including hypoechoicity, irregularity, vascularity, and microcalcification was also validated.

RESULTS

Of 157 patients (median age = 67.1 years, median prostate-specific antigen = 6.21 ng/mL) included in the study, 77 (49.0%) were diagnosed with prostate cancer (PCa), and 39 (17.0%) diagnoses were confirmed by the results of targeted cores. The existence of hypoechoic lesions was not a final predictor for PCa detection. In multivariate analysis using a combination of clinical and quantitative image analyses, the grayscale value was identified as a significant predictive factor for the presence of PCa and high-grade disease (Gleason score ≥ 7) on target lesions. The combination of clinical and image variables had the highest area under the curve (0.890) for detecting PCa in TBx.

CONCLUSIONS

The proposed method for the quantitation of hypoechoic lesions using grayscale images and HU is simple. Combined with the current clinical approaches, quantitative scoring of lesions can be useful for detecting PCa and making more precise diagnoses.

Clinical and pathologic factors predicting reclassification in active surveillance cohorts

The incidence of small, lower risk well-differentiated prostate cancer is increasing and almost half of the patients with this diagnosis are candidates for initial conservative management in an attempt to avoid overtreatment and morbidity associated with surgery or radiation. A proportion of patients labeled as low risk, candidates for Active Surveillance (AS), harbor aggressive disease and would benefit from definitive treatment. The focus of this review is to identify clinicopathologic features that may help identify these less optimal AS candidates. A systematic Medline/PubMed Review was performed in January 2017 according to PRISMA guidelines; 83 articles were selected for full text review according to their relevance and after applying limits described. For patients meeting AS criteria including Gleason Score 6, several factors can assist in predicting those patients that are at higher risk for reclassification including higher PSA density, bilateral cancer, African American race, small prostate volume and low testosterone. Nomograms combining these features improve risk stratification. Clinical and pathologic features provide a significant amount of information for risk stratification (>70%) for patients considering active surveillance. Higher risk patient subgroups can benefit from further evaluation or consideration of treatment. Recommendations will continue to evolve as data from longer term AS cohorts matures.

Comparison of Multiparametric and Biparametric MRI in First Round Cognitive Targeted Prostate Biopsy in Patients with PSA Levels under 10 ng/mL

PURPOSE

To determine the efficacy of cognitive targeted prostate biopsy using biparametric magnetic resonance imaging (b-MRI) for patients with prostate-specific antigen levels under 10 ng/mL.

MATERIALS AND METHODS

We reviewed data from 123 consecutive patients who underwent cognitive targeted prostate biopsy using prostate MRI. Of these patients, the first 55 underwent prostate biopsy using multiparametric MRI (mp-MRI), and the remaining 68 underwent prostate biopsy using b-MRI. For b-MRI, we generated T2 weighted axial imaging and diffusion-weighted imaging sequences. We found that 62 of the 123 men had suspicious lesions on MRI (32 of the 55 men in the mp-MRI group and 30 of the 68 men in the b-MRI group). We compared the prostate cancer detection rates and the proportions of clinically significant prostate cancer between the different MRI sequences.

RESULTS

Between the two MRI groups, there were no statistically significant differences in prostate cancer detection rate and proportions of clinically significant prostate cancer (41.8% vs. 30.9%, p=0.208 and 82.6% vs. 76.2%, p=0.598). Among the 62 men who had suspicious lesions on MRI, the prostate cancer detection rates were 62.5% and 63.3% (p=0.709) in the mp-MRI and b-MRI groups, respectively, and the proportions of clinically significant prostate cancer were 95.0% and 84.2% (p=0.267).

CONCLUSION

Prostate biopsy using b-MRI showed similar performance to that using mp-MRI for detecting prostate cancer and clinically significant prostate cancer. Considering the satisfactory performance and cost effectiveness of b-MRI, this technique could be a good option for obtaining intraprostatic information for first round prostate biopsy.

Development of a new nomogram to predict insignificant prostate cancer in patients undergoing radical prostatectomy

OBJECTIVE

The aim of this study was to develop a nomogram to predict the probability of insignificant prostate cancer.

MATERIALS AND METHODS

A retrospective analysis was conducted of patients who underwent radical prostatectomy at a Korean hospital between January 2005 and December 2014. Patients with pathologically insignificant prostate cancer were defined as having organ-confined disease with tumor volume less than 0.5 cm³ without Gleason scores of 4 or 5. Multivariable logistic regression analysis with a stepwise selection was used to model the relationship between preoperative characteristics and insignificant prostate cancer, and a nomogram to predict the probability of insignificant prostate cancer was created. Receiver operating characteristics (ROC) analysis was performed to assess the predictive value of the model.

RESULTS

The final study population consisted of 1343 patients. Among these patients, insignificant prostate cancer was confirmed in 188 men (14.0%) at the time of prostatectomy. Six independent predictors of insignificant prostate cancer were identified: number of positive cores (p < 0.001), maximal single core tumor involvement (p < 0.001), biopsy Gleason score (p < 0.001), prostate volume (p = 0.024), patient age (p < 0.001) and prostate-specific antigen density (p < 0.001) in the multivariable model. A nomogram to predict insignificant prostate cancer was developed using these six preoperative characteristics. The area under the ROC curve for nomogram predictions was 0.87.

CONCLUSION

The nomogram developed in this paper identifies the probability of insignificant prostate cancer and gives providers more information to guide their clinical decisions.

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.

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.

Role of PI-RADSv2 with multiparametric MRI in determining who needs active surveillance or definitive treatment according to PRIAS

PURPOSE

To evaluate the role of Prostate Imaging Reporting and Data System v. 2 (PI-RADSv2) in triaging patients with prostate cancer according to Prostate Cancer Research International: Active Surveillance (PRIAS).

MATERIALS AND METHODS

Between January 2012 and December 2014, 456 patients with biopsy-proven cancer underwent multiparametric 3T magnetic resonance imaging (MRI) using T₂ -weighted, diffusion-weighted, and dynamic contrast-enhanced MRI sequences, and then radical prostatectomy. Two radiologists independently reviewed MR images using PI-RADSv2. For AS, PRIAS required clinical stage <T3, prostate-specific antigen (PSA) ≤10 ng/mL, PSA density <0.2 ng/mL² , Gleason score (GS) ≤6, and the number of positive cores ≤2. For AS, PI-RADSv2 required an index lesion scored <4. Standard reference was prostatectomy, in which insignificant cancer was defined as a small (<0.5 cm³ ) organ-confined lesion with GS ≤6. Sensitivity and specificity for insignificant cancer were obtained with PRIAS, PI-RADSv2, and both.

RESULTS

The sensitivity and specificity with PRIAS were 82.9% (68/82) and 70.9% (265/374), respectively. PI-RADSv2 decreased the sensitivity to 61% (50/82) to 80.5% (66/82), but increased the specificity to 77.8% (291/374) to 90.8% (340/374). The combination of PRIAS and PI-RDASv2 increased significantly the specificity to 89.6% (335/374) to 92.8% (347/374) (P < 0.001).

CONCLUSION

PRIAS using multiparametric MRI can identify a greater number of insignificant cancers than PI-RADSv2. However, PI-RADSv2 helps detect many significant cancers that are misdiagnosed as insignificant cancer with PRIAS.

LEVEL OF EVIDENCE

3 Technical Efficacy: Stage 2 J. MAGN. RESON. IMAGING 2017;45:1753-1759.

Magnetic resonance imaging in active surveillance of prostate cancer: a systematic review

CONTEXT

There is great interest in using magnetic resonance imaging (MRI) for men on active surveillance for prostate cancer.

OBJECTIVE

To systematically review evidence regarding the use of MRI in men with low- or intermediate-risk prostate cancer suitable for active surveillance.

EVIDENCE ACQUISITION

Ovid Medline and Embase databases were searched for active surveillance, prostate cancer, and MRI from inception until April 25, 2014 according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses process. Identified reports were critically appraised according to the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) criteria.

EVIDENCE SYNTHESIS

A lesion on MRI suspicious for prostate cancer (positive MRI) is seen in two-thirds of men otherwise suitable for active surveillance. A positive MRI makes the identification of clinically significant disease at repeat biopsy more likely, especially when biopsies are targeted to suspicious MRI lesions. Radical prostatectomy data show that positive MRI is more likely to be associated with upgrading (Gleason score>3+3) than a negative MRI (43% vs 27%). A positive MRI is not significantly more likely to be associated with upstaging at radical prostatectomy (>T2) than a negative MRI (10% vs 8%). Although MRI is of interest in the monitoring of men on active surveillance, robust data on the use of repeat MRI in active surveillance are lacking. Prospective studies with clear definitions of radiological significance and progression are needed before this approach can be adopted.

CONCLUSIONS

MRI is useful for detection of clinically significant disease at initial assessment of men considering active surveillance. To use MRI as a monitoring tool in surveillance, it will be necessary to define both radiological significance and radiological progression.

PATIENT SUMMARY

This review assesses evidence for the use of magnetic resonance imaging (MRI) in men on active surveillance for prostate cancer. MRI at the start of surveillance can detect clinically significant disease in one-third to half of men. There are few data to assess the use of MRI as a monitoring tool during surveillance, so there is a need to define significant disease on MRI and significant changes over time.

Magnetic resonance-invisible versus magnetic resonance-visible prostate cancer in active surveillance: a preliminary report on disease outcomes

OBJECTIVE

To assess the association between magnetic resonance (MR) appearance of prostate cancer on a baseline multiparametric prostate (MP) MR imaging (MRI) and biopsy outcome in men with favorable-risk prostate cancer managed with active surveillance (AS).

MATERIALS AND METHODS

Ninety-six consecutive men (mean age, 67.8 years) who had a baseline MP MRI within 1 year of AS enrollment were included in the study. MP MRI results were analyzed to identify men with MR-invisible tumor defined as no signal abnormality on T2-weighted images, no focal restricted diffusion, and no perfusion abnormality on dynamic contrast-enhanced images. Patients with (n = 84) or without (n = 12) MR-visible tumor were compared and the impact of MR-invisibility of tumor on the risk of adverse biopsy pathology based on the Epstein criteria was investigated with a median follow-up of 23 months.

RESULTS

Adverse biopsy pathology occurred in 36.5% (35 of 96) of patients. There was no significant difference in the fulfillment of AS criteria at enrollment, prostate-specific antigen level or density, prostate volume, and number of biopsies (total or after MRI) between the 2 groups of patients. A total of 8.3% (1 of 12) of men with MR-invisible tumor had adverse biopsy pathology as compared with 40.5% (34 of 84) of men with MR-visible tumors. The MR-invisibility of tumor was associated with a lower risk of adverse biopsy pathology (crude relative risk = 0.35; 95% confidence interval, 0.10-1.25; prostate-specific antigen density-adjusted relative risk = 0.21; 95% confidence interval, 0.03-1.32).

CONCLUSION

The MR-invisibility of tumor on MP MRI could be of prognostic significance in monitoring men in AS with potential benefit of tailoring the frequency of surveillance biopsies and reducing the number of unnecessary biopsies.

Multiparametric 3T MRI for the prediction of pathological downgrading after radical prostatectomy in patients with biopsy-proven Gleason score 3 + 4 prostate cancer

OBJECTIVES

The aim of this study was to assess the diagnostic performance of pre-treatment 3-Tesla (3T) multiparametric magnetic resonance imaging (mpMRI) for predicting Gleason score (GS) downgrading after radical prostatectomy (RP) in patients with GS 3 + 4 prostate cancer (PCa) on biopsy.

METHODS

We retrospectively reviewed 304 patients with biopsy-proven GS 3 + 4 PCa who underwent mpMRI before RP. On T2-weighted imaging and three mpMRI combinations (T2-weighted imaging + diffusion-weighted imaging [DWI], T2-weighted imaging + dynamic contrast-enhanced-MRI [DCE-MRI], and T2-weighted imaging + DWI + DCE-MRI), two radiologists (R1/R2) scored the presence of a dominant tumour using a 5-point Likert scale (1 = definitely absent to 5 = definitely present). Diagnostic performance in identifying downgrading was evaluated via areas under the curves (AUCs). Predictive accuracies of multivariate models were calculated.

RESULTS

In predicting downgrading, T2-weighted imaging + DWI (AUC = 0.89/0.85 for R1/R2) performed significantly better than T2-weighted imaging alone (AUC = 0.72/0.73; p < 0.001/p = 0.02 for R1/R2), while T2-weighted imaging + DWI + DCE-MRI (AUC = 0.89/0.84 for R1/R2) performed no better than T2-weighted imaging + DWI (p = 0.48/p > 0.99 for R1/R2). On multivariate analysis, the clinical + mpMRI model incorporating T2-weighted imaging + DWI (AUC = 0.92/0.88 for R1/R2) predicted downgrading significantly better than the clinical model (AUC = 0.73; p < 0.001 for R1/R2).

CONCLUSION

mpMRI improves the ability to identify a subgroup of patients with Gleason 3 + 4 PCa on biopsy who are candidates for active surveillance. DCE-MRI (compared to T2 + DWI) offered no additional benefit to the prediction of downgrading.

KEY POINTS

Diagnostic performance of T2-weighted-imaging + DWI was better than T2-weighted-imaging alone. Diagnostic performance of T2-weighted-imaging + DWI was similar to T2-weighted-imaging + DWI + DCE-MRI. Combining clinical and T2-weighted-imaging + DWI features best predicted GS downgrading. mpMRI might prevent overtreatment by increasing eligibility for PCa active surveillance.

Seventh Joint Meeting of K-J-CaP and CaPSURE: extending the global initiative to improve prostate cancer management

This report summarizes the presentations and discussions that took place at the Seventh Joint Meeting of the Korea–Japan Study Group of Prostate Cancer (K-J-CaP) and the Cancer of the Prostate Strategic Urologic Research Endeavor (CaPSURE) held in Seoul, Korea, in September 2013. The original J-CaP and CaPSURE Joint Initiative has now been established since 2007 and since the initial collaboration between research teams in the United States (US) and Japan, the project has expanded to include several other Asian countries. The objective of the initiative is to analyze and compare data for prostate cancer patients in the participating countries, looking at similarities and differences in patient management and outcomes. Until now the focus has been primarily on data generated within J-CaP and CaPSURE, both large-scale, longitudinal, observational databases of prostate cancer patients in Japan and the US, respectively. This year’s meeting was hosted for the first time in Korea which has recently established its own national database–K-CaP–to add to the wealth of data generated by J-CaP and CaPSURE. As a newly-developed database, K-CaP has also provided a valuable ‘template’ for other countries, such as China and Indonesia, planning to establish their own national databases and this will ultimately allow greater opportunities for international data comparisons. A range of topics was discussed at this Seventh Joint Meeting including comparison of outcomes following androgen deprivation therapy or radical prostatectomy in patients with localized prostate cancer, the use of active surveillance as a treatment option and the triggers for intervention when employing this regimen, patient quality of life during treatment, the impact of comorbidities on outcomes, and a comparison of recent outcomes data between J-CaP and CaPSURE. The participants recognized that prostate cancer was now a global disease and therefore major insights into understanding and improving the management of this condition would arise from global interactions such as this joint initiative.