Magnetic Resonance Imaging Should Be Used in the Active Surveillance of Patients with Localised Prostate Cancer

Evaluating the Role of Ultrasound in Prostate Cancer trial - phase 1: Early experience of micro-ultrasound in the United Kingdom

Purpose

The purpose of this study was to evaluate if the use of micro-ultrasound can detect clinically significant prostate pathology when compared to histology obtained during a transperineal prostate biopsy.

Methods

Patients suspected of having prostate cancer, who had a pre-biopsy magnetic resonance imaging and could tolerate a transrectal examination, were prospectively recruited. All patients had a micro-ultrasound scan prior to their biopsy. The findings of magnetic resonance imaging, micro-ultrasound and histology were risk stratified in accordance with local pathways. Comparison of assigned risk scores was made using histology as the reference standard.

Results

Data from 101 patients were evaluated. Histology showed that clinically significant prostate cancer was detected in 48.5% (n = 49/101) of patients. Moderate inter-rater agreement was found in both magnetic resonance imaging and micro-ultrasound with К of 0.31 in both modalities. High-risk findings were identified in 81% (n = 82/101) patients at magnetic resonance imaging and in 66% (n = 67/101) patients at micro-ultrasound. Sensitivity and specificity of magnetic resonance imaging were found to be 87% and 34.6% and for micro-ultrasound 73.3% and 53.8%, respectively.

Conclusion

A limitation of this study was that the biopsy was not performed with micro-ultrasound which may have resulted in unidentified cancers and lowered the apparent accuracy of the technique. However, we conclude that while micro-ultrasound was diagnostic, magnetic resonance imaging demonstrated higher sensitivity in our local population and remains the pre-biopsy imaging modality of choice. However, the higher specificity of micro-ultrasound identified does indicate that it may be of value when magnetic resonance imaging is contraindicated. The role of micro-ultrasound, within an active surveillance pathway for prostate cancer, warrants further investigation.

A Multivariable Approach Using Magnetic Resonance Imaging to Avoid a Protocol-based Prostate Biopsy in Men on Active Surveillance for Prostate Cancer-Data from the International Multicenter Prospective PRIAS Study

BACKGROUND

There is ongoing discussion whether a multivariable approach including magnetic resonance imaging (MRI) can safely prevent unnecessary protocol-advised repeat biopsy during active surveillance (AS).

OBJECTIVE

To determine predictors for grade group (GG) reclassification in patients undergoing an MRI-informed prostate biopsy (MRI-Bx) during AS and to evaluate whether a confirmatory biopsy can be omitted in patients diagnosed with upfront MRI.

DESIGN, SETTING, AND PARTICIPANTS

The Prostate cancer Research International: Active Surveillance (PRIAS) study is a multicenter prospective study of patients on AS (www.prias-project.org). We selected all patients undergoing MRI-Bx (targeted ± systematic biopsy) during AS.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

A time-dependent Cox regression analysis was used to determine the predictors of GG progression/reclassification in patients undergoing MRI-Bx. A sensitivity analysis and a multivariable logistic regression analysis were also performed.

RESULTS AND LIMITATIONS

A total of 1185 patients underwent 1488 MRI-Bx sessions. The time-dependent Cox regression analysis showed that age (per 10 yr, hazard ratio [HR] 0.84 [95% confidence interval {CI} 0.71-0.99]), MRI outcome (Prostate Imaging Reporting and Data System [PIRADS] 3 vs negative HR 2.46 [95% CI 1.56-3.88], PIRADS 4 vs negative HR 3.39 [95% CI 2.28-5.05], and PIRADS 5 vs negative HR 4.95 [95% CI 3.25-7.56]), prostate-specific antigen (PSA) density (per 0.1 ng/ml cm³, HR 1.20 [95% CI 1.12-1.30]), and percentage positive cores on the last systematic biopsy (per 10%, HR 1.16 [95% CI 1.10-1.23]) were significant predictors of GG reclassification. Of the patients with negative MRI and a PSA density of <0.15 ng/ml cm³ (n = 315), 3% were reclassified to GG ≥2 and 0.6% to GG ≥3. At the confirmatory biopsy, reclassification to GG ≥2 and ≥3 was observed in 23% and 7% of the patients diagnosed without upfront MRI and in 19% and 6% of the patients diagnosed with upfront MRI, respectively. The multivariable analysis showed no significant difference in upgrading at the confirmatory biopsy between patients diagnosed with or without upfront MRI.

CONCLUSIONS

Age, MRI outcome, PSA density, and percentage positive cores are significant predictors of reclassification at an MRI-informed biopsy. Patients with negative MRI and a PSA density of <0.15 ng/ml cm³ can safely omit a protocol-based prostate biopsy, whereas in other patients, a multivariable approach is advised. Being diagnosed with upfront MRI appears not to significantly affect reclassification risk; hence, a confirmatory MRI-Bx cannot totally be omitted yet.

PATIENT SUMMARY

A protocol-based prostate biopsy while on active surveillance can be omitted in patients with negative magnetic resonance imaging (MRI) and prostate-specific antigen density <0.15 ng/ml cm³. A confirmatory biopsy cannot simply be omitted in all patients diagnosed with upfront MRI.

Active surveillance for prostate cancer

Many men diagnosed with localized prostate cancer can postpone definitive treatment without raising their risk of metastasis or death from disease. Active surveillance (AS) is a method of monitoring select men, with the option of switching to active treatment upon signs of progression, thereby avoiding the well-known side-effects of surgery and radiotherapy. This review analyzes the data from long-running AS cohorts to determine the safety and efficacy of AS. We conducted a narrative review of recently published data, including 14 articles from 13 AS cohorts. The cohorts used varying inclusion criteria, with reported differences in clinical T stage and Gleason Score (Grade Group), among other features. Some studies (n=5) limited their cohorts to low-risk patients, while others (n=8) also included intermediate-risk patients. The heterogeneity of the cohorts produced mixed results, with the risk of prostate cancer metastasis ranging from 0.1–1.0% at 10 years and the risk of prostate cancer mortality ranging from 0–1.9% at 10 years. However, the majority of studies reported risks of less than 0.5% at 10 years for both metastasis and death. For most cohorts, half of men remained untreated for 5–10 years, with estimates ranging from 37% receiving active treatment in the Toronto cohort to 73% in the Prostate Cancer Research International AS (PRIAS) study. Current data do not support the use of negative magnetic resonance imaging (MRI) to avoid scheduled biopsy. Taken together, the data collected from these AS cohorts suggests that AS is a safe approach for men with low-grade prostate cancer and some men with intermediate risk disease. AS should be more broadly implemented for eligible patients to avoid the decreases in quality of life from undergoing active treatment. Studies expanding the inclusion criteria and further defining a subset of men with favorable intermediate-risk prostate cancer who might safely benefit from AS are needed to assess the long-term outcomes of using AS in intermediate-risk groups.

Insights into Urological Cancer

The year the Covid-19 pandemic appeared has been quite prolific in urological cancer research, and the collection of articles, perspectives, and reviews on renal, prostate, and urinary tract tumors merged in this Urological Cancer 2020 issue is just a representative sample of this assertion [...].

Personalised biopsy schedules based on risk of Gleason upgrading for patients with low-risk prostate cancer on active surveillance

OBJECTIVE

To develop a model and methodology for predicting the risk of Gleason upgrading in patients with prostate cancer on active surveillance (AS) and using the predicted risks to create risk-based personalised biopsy schedules as an alternative to one-size-fits-all schedules (e.g. annually). Furthermore, to assist patients and doctors in making shared decisions on biopsy schedules, by providing them quantitative estimates of the burden and benefit of opting for personalised vs any other schedule in AS. Lastly, to externally validate our model and implement it along with personalised schedules in a ready to use web-application.

PATIENTS AND METHODS

Repeat prostate-specific antigen (PSA) measurements, timing and results of previous biopsies, and age at baseline from the world's largest AS study, Prostate Cancer Research International Active Surveillance (PRIAS; 7813 patients, 1134 experienced upgrading). We fitted a Bayesian joint model for time-to-event and longitudinal data to this dataset. We then validated our model externally in the largest six AS cohorts of the Movember Foundation's third Global Action Plan (GAP3) database (>20 000 patients, 27 centres worldwide). Using the model predicted upgrading risks; we scheduled biopsies whenever a patient's upgrading risk was above a certain threshold. To assist patients/doctors in the choice of this threshold, and to compare the resulting personalised schedule with currently practiced schedules, along with the timing and the total number of biopsies (burden) planned, for each schedule we provided them with the time delay expected in detecting upgrading (shorter is better).

RESULTS

The cause-specific cumulative upgrading risk at the 5-year follow-up was 35% in PRIAS, and at most 50% in the GAP3 cohorts. In the PRIAS-based model, PSA velocity was a stronger predictor of upgrading (hazard ratio [HR] 2.47, 95% confidence interval [CI] 1.93-2.99) than the PSA level (HR 0.99, 95% CI 0.89-1.11). Our model had a moderate area under the receiver operating characteristic curve (0.6-0.7) in the validation cohorts. The prediction error was moderate (0.1-0.2) in theGAP3 cohorts where the impact of the PSA level and velocity on upgrading risk was similar to PRIAS, but large (0.2-0.3) otherwise. Our model required re-calibration of baseline upgrading risk in the validation cohorts. We implemented the validated models and the methodology for personalised schedules in a web-application (http://tiny.cc/biopsy).

CONCLUSIONS

We successfully developed and validated a model for predicting upgrading risk, and providing risk-based personalised biopsy decisions in AS of prostate cancer. Personalised prostate biopsies are a novel alternative to fixed one-size-fits-all schedules, which may help to reduce unnecessary prostate biopsies, while maintaining cancer control. The model and schedules made available via a web-application enable shared decision-making on biopsy schedules by comparing fixed and personalised schedules on total biopsies and expected time delay in detecting upgrading.

Oligometastatic Prostate Adenocarcinoma. Clinical-Pathologic Study of a Histologically Under-Recognized Prostate Cancer

The clinical parameters and the histological and immunohistochemical findings of a prospective protocolized series of 27 prostate carcinoma patients with oligometastatic disease followed homogeneously were analyzed. Lymph nodes (81.5%) and bones (18.5%) were the only metastatic sites. Local control after metastatic directed treatment was achieved in 22 (81.5%) patients. A total of 8 (29.6%) patients developed castration-resistant prostate cancer. Seventeen (63%) patients presented with non-organ confined disease. The Gleason index 8-10 was the most frequently observed (12 cases, 44.4%) combined grade. Positive immunostainings were detected with androgen receptor (100%), PGP 9.5 (74%), ERG (40.7%), chromogranin A (29.6%), and synaptophysin (18.5%) antibodies. The Ki-67 index value > 5% was observed in 15% of the cases. L1CAM immunostaining was negative in all cases. Fisher exact test showed that successful local control of metastases was associated to mild inflammation, organ confined disease, Ki-67 index < 5%, and Gleason index 3 + 3. A castration resistant status was associated with severe inflammation, atrophy, a Gleason index higher than 3 + 3, Ki-67 index ≥ 5%, and positive PGP 9.5, chromogranin A, and synaptophysin immunostainings. In conclusion, oligometastatic prostate adenocarcinoma does not have a specific clinical-pathologic profile. However, some histologic and immunohistochemical parameters of routine use may help with making therapeutic decisions.

Role of Multiparametric Prostate Magnetic Resonance Imaging before Confirmatory Biopsy in Assessing the Risk of Prostate Cancer Progression during Active Surveillance

Objective

To evaluate the impact of multiparametric magnetic resonance imaging (mpMRI) before confirmatory prostate biopsy in patients under active surveillance (AS).

Materials and Methods

This retrospective study included 170 patients with Gleason grade 6 prostate cancer initially enrolled in an AS program between 2011 and 2019. Prostate mpMRI was performed using a 1.5 tesla (T) magnetic resonance imaging system with a 16-channel phased-array body coil. The protocol included T1-weighted, T2-weighted, diffusion-weighted, and dynamic contrast-enhanced imaging sequences. Uroradiology reports generated by a specialist were based on prostate imaging-reporting and data system (PI-RADS) version 2. Univariate and multivariate analyses were performed based on regression models.

Results

The reclassification rate at confirmatory biopsy was higher in patients with suspicious lesions on mpMRI (PI-RADS score ≥ 3) (n = 47) than in patients with non-suspicious mpMRIs (n = 61) and who did not undergo mpMRIs (n = 62) (66%, 26.2%, and 24.2%, respectively; p < 0.001). On multivariate analysis, presence of a suspicious mpMRI finding (PI-RADS score ≥ 3) was associated (adjusted odds ratio: 4.72) with the risk of reclassification at confirmatory biopsy after adjusting for the main variables (age, prostate-specific antigen density, number of positive cores, number of previous biopsies, and clinical stage). Presence of a suspicious mpMRI finding (adjusted hazard ratio: 2.62) was also associated with the risk of progression to active treatment during the follow-up.

Conclusion

Inclusion of mpMRI before the confirmatory biopsy is useful to stratify the risk of reclassification during the biopsy as well as to evaluate the risk of progression to active treatment during follow-up.

Moving away from systematic biopsies: image-guided prostate biopsy (in-bore biopsy, cognitive fusion biopsy, MRUS fusion biopsy) -literature review

OBJECTIVE

To compare the detection rate of clinically significant cancer (CSCa) by magnetic resonance imaging-targeted biopsy (MRI-TB) with that by standard systematic biopsy (SB) and to evaluate the role of MRI-TB as a replacement from SB in men at clinical risk of prostate cancer.

METHODS

The non-systematic literature was searched for peer-reviewed English-language articles using PubMed, including the prospective paired studies, where the index test was MRI-TB and the comparator text was SB. Also the randomized clinical trials (RCTs) are included if one arm was MRI-TB and another arm was SB.

RESULTS

Eighteen prospective studies used both MRI-TB and TRUS-SB, and eight RCT received one of the tests for prostate cancer detection. In most prospective trials to compare MRI-TB vs. SB, there was no significant difference in any cancer detection rate; however, MRI-TB detected more men with CSCa and fewer men with CISCa than SB.

CONCLUSION

MRI-TB is superior to SB in detection of CSCa. Since some significant cancer was detected by SB only, a combination of SB with the TB technique would avoid the underdiagnosis of CSCa.

Utility of multiparametric magnetic resonance imaging in the risk stratification of men with Grade Group 1 prostate cancer on active surveillance

OBJECTIVE

To assess if the adoption of multiparametric magnetic resonance imaging (mpMRI) in active surveillance (AS) has improved the identification of occult higher-grade prostate cancer (PCa).

PATIENTS AND METHODS

We retrospectively identified men from the Johns Hopkins AS registry enrolled since 2013 (year of mpMRI adoption) with Grade Group (GG) 1 PCa and who underwent a single mpMRI. Men in this group were dichotomised by the presence (n = 207) or absence (negative mpMRI, n = 225) of one or more lesions with a Prostate Imaging-Reporting and Data System (PI-RADS) score of ≥ 3. Both groups were compared to a third cohort of men with GG1 PCa enrolled in AS prior to 2013 (pre-mpMRI era, n = 669). The risk of upgrading to GG ≥ 2 PCa on follow-up biopsies (performed with or without MRI targeting) was evaluated among the groups using survival analysis.

RESULTS

Men in both mpMRI groups underwent a median (interquartile range [IQR]) of 2 (2-3) biopsies separated by a median (IQR) interval of 13 (12-16) months, whereas men in the pre-MRI era underwent a median (IQR) of 3 (2-5) biopsies, separated by a median (IQR) interval of 12 (12-14) months. The 2- and 4-year upgrade-free survival rates were 93% and 83%, 74% and 59%; and, 87% and 76% for the negative mpMRI, PI-RADS ≥ 3, and pre-mpMRI-era groups, respectively (P < 0.001). On multivariable analysis, both mpMRI groups had significantly different risk of upgrading compared to pre-mpMRI-era group (negative mpMRI group: hazard ratio [HR] 0.61, 95% confidence interval [CI] 0.39-0.95, P = 0.03; PI-RADS ≥ 3 group: HR 1.96, 95% CI 1.36-2.82, P < 0.001).

CONCLUSIONS

mpMRI improves the risk stratification of men on AS and should be used to aid enrolment and monitoring decisions.