Role of MRI in low-risk prostate cancer: finding the wolf in sheep's clothing or the sheep in wolf's clothing?

[Active surveillance of prostate cancer]

The aim of active surveillance (AS) is to avoid overtreatment of clinically insignificant prostate cancer (PCa). It is now strongly recommended for patients diagnosed with localized low-risk PCa. Additionally, it can be considered for selected patients with localized PCa in the International Society of Urological Pathology (ISUP) group 2, provided patients have a favorable risk profile. This profile is histopathologically characterized by the presence of a low percentage of Gleason pattern 4 and the absence of cribriform or intraductal components. The role of magnetic resonance imaging (MRI), including the Prostate Cancer Radiological Estimation of Change in Sequential Evaluation (PRECISE) recommendations on monitoring is increasing. It is crucial to adhere to defined intervals for prostate-specific antigen (PSA) level checks, repeat biopsies, MRI and further targeted and systematic biopsies under AS. The MRI of the prostate (according to the current recommendations as multiparametric MRI, mpMRI), as a noninvasive diagnostic tool, has the potential to be used as a decision aid for determining the need for repeated biopsies during AS. As the trigger for deciding for an active treatment PSA progression alone is not sufficient but there must be a biopsy-confirmed tumor progression with an upgrading. This continuing medical education (CME) article summarizes the current indications, procedures and discontinuation criteria for AS based on the latest evidence and an adaptation to international guidelines.

Utilizing lesion diameter and prostate specific antigen density to decide on magnetic resonance imaging guided confirmatory biopsy of prostate imaging reporting and data system score three lesions in African American prostate cancer patients managed with active surveillance

OBJECTIVE

The objective of the study is to identify the rate of significant prostate cancer (PCa) detection in PI-RADS3 lesions in AA patients stratified by PSAD threshold of < 0.15 vs. ≥ 0.15 ng/ml² and lesion diameter of < 1 cm vs ≥ 1 cm.

METHODS

We analyzed our institutional database of MRI-TB to identify the rate of significant prostate cancer (PCa) detection in PI-RADS3 lesions in AA patients stratified by PSAD threshold of < 0.15 vs. ≥ 0.15 ng/ml² and lesion diameter of < 1 cm vs ≥ 1 cm. Significant prostate cancer was defined as Gleason grade group 2 or higher on MRI-TB of the PI-RADS 3 lesion.

RESULTS

Of 768 patients included in the database, 211 (27.5%) patients identified themselves as AAs. Mean age of AA patients was 63 years and mean PSAD was 0.21. Sixty nine (32.7%) AA patients were found to have PI-RADS 3 lesions. Mean PSAD of AA patients with PI-RADS 3 lesions was 0.21 ng/ml² as well. Fifty percent of AA patients with PI-RADS 3 lesions had PSAD ≥ 0.15 ng/ml². Significant PCa detection rate for AA patients with PI-RADS 3 lesions was 9% for PSAD of ≥ 0.15 vs. 0.03% percent for AA patients with PSAD < 0.15 ng/ml² (OR 7.056, CI 1.017-167.9, P = 0.04). Stratification by lesion diameter (< 1 cm vs. > 1 cm) resulted in missing 0% of significant PCa when only AA patients with PSAD ≥ 0.15 ng/ml² and lesion diameter ≥ 1 cm received MRI-TB.

CONCLUSIONS

We report on the performance of a reported PSAD density threshold in detecting significant PCa in one of the largest series of AA patients receiving MRI-TB of the prostate. Our results have direct clinical implications when counseling AA patients with PI-RADS 3 lesion on whether they should undergo MRI-TB of such lesions.

Prostate Cancer Radiogenomics-From Imaging to Molecular Characterization

Radiomics and genomics represent two of the most promising fields of cancer research, designed to improve the risk stratification and disease management of patients with prostate cancer (PCa). Radiomics involves a conversion of imaging derivate quantitative features using manual or automated algorithms, enhancing existing data through mathematical analysis. This could increase the clinical value in PCa management. To extract features from imaging methods such as magnetic resonance imaging (MRI), the empiric nature of the analysis using machine learning and artificial intelligence could help make the best clinical decisions. Genomics information can be explained or decoded by radiomics. The development of methodologies can create more-efficient predictive models and can better characterize the molecular features of PCa. Additionally, the identification of new imaging biomarkers can overcome the known heterogeneity of PCa, by non-invasive radiological assessment of the whole specific organ. In the future, the validation of recent findings, in large, randomized cohorts of PCa patients, can establish the role of radiogenomics. Briefly, we aimed to review the current literature of highly quantitative and qualitative results from well-designed studies for the diagnoses, treatment, and follow-up of prostate cancer, based on radiomics, genomics and radiogenomics research.

Biomarker in Active Surveillance for Prostate Cancer: A Systematic Review

Active surveillance (AS) in prostate cancer (PCa) represents a curative alternative for men with localised low-risk PCa. Continuous improvement of AS patient's selection and surveillance modalities aims at reducing misclassification, simplifying modalities of surveillance and decreasing need for invasive procedures such repeated biopsies. Biomarkers represent interesting tools to evaluate PCa diagnosis and prognosis, of which many are readily available or under evaluation. The aim of this review is to investigate the biomarker performance for AS selection and patient outcome prediction. Blood, urinary and tissue biomarkers were studied and a brief description of use was proposed along with a summary of major findings. Biomarkers represent promising tools which could be part of a more tailored risk AS strategy aiming to offer personalized medicine and to individualize the treatment and monitoring of each patient. The usefulness of biomarkers has mainly been suggested for AS selection, whereas few studies have investigated their role during the monitoring phase. Randomized prospective studies dealing with imaging are needed as well as larger prospective studies with long-term follow-up and strong oncologic endpoints.

Multiparametric MRI in Active Surveillance of Prostate Cancer: An Overview and a Practical Approach

MRI has become important for the detection of prostate cancer. MRI-guided biopsy is superior to conventional systematic biopsy in patients suspected with prostate cancer. MRI is also increasingly used for monitoring patients with low-risk prostate cancer during active surveillance. It improves patient selection for active surveillance at diagnosis, although its role during follow-up is unclear. We aim to review existing evidence and propose a practical approach for incorporating MRI into active surveillance protocols.

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.

EAU-EANM-ESTRO-ESUR-SIOG Guidelines on Prostate Cancer-2020 Update. Part 1: Screening, Diagnosis, and Local Treatment with Curative Intent

OBJECTIVE

To present a summary of the 2020 version of the European Association of Urology (EAU)-European Association of Nuclear Medicine (EANM)-European Society for Radiotherapy and Oncology (ESTRO)-European Society of Urogenital Radiology (ESUR)-International Society of Geriatric Oncology (SIOG) guidelines on screening, diagnosis, and local treatment of clinically localised prostate cancer (PCa).

EVIDENCE ACQUISITION

The panel performed a literature review of new data, covering the time frame between 2016 and 2020. The guidelines were updated and a strength rating for each recommendation was added based on a systematic review of the evidence.

EVIDENCE SYNTHESIS

A risk-adapted strategy for identifying men who may develop PCa is advised, generally commencing at 50 yr of age and based on individualised life expectancy. Risk-adapted screening should be offered to men at increased risk from the age of 45 yr and to breast cancer susceptibility gene (BRCA) mutation carriers, who have been confirmed to be at risk of early and aggressive disease (mainly BRAC2), from around 40 yr of age. The use of multiparametric magnetic resonance imaging in order to avoid unnecessary biopsies is recommended. When a biopsy is performed, a combination of targeted and systematic biopsies must be offered. There is currently no place for the routine use of tissue-based biomarkers. Whilst prostate-specific membrane antigen positron emission tomography computed tomography is the most sensitive staging procedure, the lack of outcome benefit remains a major limitation. Active surveillance (AS) should always be discussed with low-risk patients, as well as with selected intermediate-risk patients with favourable International Society of Urological Pathology (ISUP) 2 lesions. Local therapies are addressed, as well as the AS journey and the management of persistent prostate-specific antigen after surgery. A strong recommendation to consider moderate hypofractionation in intermediate-risk patients is provided. Patients with cN1 PCa should be offered a local treatment combined with long-term hormonal treatment.

CONCLUSIONS

The evidence in the field of diagnosis, staging, and treatment of localised PCa is evolving rapidly. The 2020 EAU-EANM-ESTRO-ESUR-SIOG guidelines on PCa summarise the most recent findings and advice for their use in clinical practice. These PCa guidelines reflect the multidisciplinary nature of PCa management.

PATIENT SUMMARY

Updated prostate cancer guidelines are presented, addressing screening, diagnosis, and local treatment with curative intent. These guidelines rely on the available scientific evidence, and new insights will need to be considered and included on a regular basis. In some cases, the supporting evidence for new treatment options is not yet strong enough to provide a recommendation, which is why continuous updating is important. Patients must be fully informed of all relevant options and, together with their treating physicians, decide on the most optimal management for them.

A discussion on controversies and ethical dilemmas in prostate cancer screening

Prostate cancer (PCa) is one of the the most common cancers in men. A blood test called prostate-specific antigen (PSA) has a potential to pick up this cancer very early and is used for screening of this disease. However, screening for prostate cancer is a matter of debate. Level 1 evidence from randomised controlled trials suggests a reduction in cancer-specific mortality from PCa screening. However, there could be an associated impact on quality of life due to a high proportion of overdiagnosis and overtreatment as part of the screening. The US Preventive Services Task Force (USPSTF) in 2012 recommended that PSA-based PCa screening should not to be offered at any age. However, considering the current evidence, USPSTF recently revised its recommendation to offer the PSA test to men aged 55-69 years with shared decision-making, in line with earlier guidelines from the American Cancer Society and the American Urological Association. A shared decision making is necessary since the PSA test could potentially harm an individual. However, the literature suggests that clinicians often neglect a discussion on this issue before ordering the test. This narrative discusses the main controversies regarding PCa screening including the PSA threshold for biopsy, the concept of overdiagnosis and overtreatment, the practical difficulties of active surveillance, the current level 1 evidence on the mortality benefit of screening, and the associated pitfalls. It offers a detailed discussion on the ethics involved in the PSA test and highlights the barriers to shared decision-making and possible solutions.

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.

The current role of prostate multiparametric magnetic resonance imaging

Prostate multi-parametric magnetic resonance imaging (mpMRI) has shown excellent sensitivity for Gleason ≥7 cancers, especially when their volume is ≥0.5 mL. As a result, performing an mpMRI before prostate biopsy could improve the detection of clinically significant prostate cancer (csPCa) by adding targeted biopsies to systematic biopsies. Currently, there is a consensus that targeted biopsies improve the detection of csPCa in the repeat biopsy setting and at confirmatory biopsy in patients considering active surveillance. Several prospective multicentric controlled trials recently showed that targeted biopsy also improved csPCa detection in biopsy-naïve patients. The role of mpMRI and targeted biopsy during the follow-up of active surveillance remains unclear. Whether systematic biopsy could be omitted in case of negative mpMRI is also a matter of controversy. mpMRI did show excellent negative predictive values (NPV) in the literature, however, since NPV depends on the prevalence of the disease, negative mpMRI findings should be interpreted in the light of a priori risk for csPCa of the patient. Nomograms combining mpMRI findings and classical risk predictors (age, prostate-specific antigen density, digital rectal examination, etc.) will probably be developed in the future to decide whether a prostate biopsy should be obtained. mpMRI has a good specificity for detecting T3 stage cancers, but its sensitivity is low. It should therefore not be used routinely for staging purposes in low-risk patients. Nomograms combining mpMRI findings and other clinical and biochemical data will also probably be used in the future to better assess the risk of T3 stage disease.

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.

Reduction of MRI-targeted biopsies in men with low-risk prostate cancer on active surveillance by stratifying to PI-RADS and PSA-density, with different thresholds for significant disease

Background

The fear of undergrading prostate cancer (PCa) in men on active surveillance (AS) have led to strict criteria for monitoring, which have resulted in good long-term cancer-specific survival, proving the safety of this approach. Reducing undergrading, MRI-targeted biopsies are increasingly used in men with low-risk disease despite their undefined role yet. The objective of this study is to investigate the rate of upgrading using MRI-targeted biopsies in men with low-risk disease on AS, stratified on the basis of PI-RADS and PSA-density, with the aim to reduce potential unnecessary repeat biopsy procedures.

Methods

A total of 331 men were prospectively enrolled following the MRI-PRIAS protocol. MR imaging was according to Prostate Imaging Reporting and Data System (PI-RADSv2) guidelines. Suspicious MRI lesions (PI-RADS 3–5) were additionally targeted by MRI-TRUS fusion biopsies. Outcome measure was upgrading to Gleason score (GS) ≥3+4 with MRI-targeted biopsies, stratified for PI-RADS and PSA-density.

Results

In total, 25% (82/331) of men on AS showed upgrading from GS 3+3. Only 3% (11/331) was upgraded to GS ≥8. In 60% (198/331) a suspicious MRI lesion was identified, but in only 41% (82/198) of men upgrading was confirmed. PI-RADS 3, 4 and 5 categorized index lesions, showed upgrading in 30%, 34% and 66% of men, respectively. Stratification to PI-RADS 4–5, instead of PI-RADS 3–5, would have missed a small number of high volume Gleason 4 PCa in PI-RADS 3 category. However, further stratification into PI-RADS 3 lesions and PSA-density <0.15 ng/mL² could result in a safe targeted biopsy reduction of 36% in this category, without missing any upgrades.

Conclusions

Stratification with the combination of PI-RADS and PSA-density may reduce unnecessary additional MRI biopsy testing. Overall, the high rate of detected upgrading in men on AS may result in an unintended tightening of continuing in AS. Since patients, included under current AS criteria showed extremely favorable outcome, there might be no need to further restrict continuing on AS with MRI and targeted biopsies.