Prostate Cancer Screening with Magnetic Resonance Imaging: Results from the Second Round of the Göteborg Prostate Cancer Screening 2 Trial

Magnetic Resonance Imaging in Prostate Cancer Screening: A Systematic Review and Meta-Analysis

Importance

Prostate magnetic resonance imaging (MRI) is increasingly integrated within the prostate cancer (PCa) early detection pathway.

Objective

To systematically evaluate the existing evidence regarding screening pathways incorporating MRI with targeted biopsy and assess their diagnostic value compared with prostate-specific antigen (PSA)-based screening with systematic biopsy strategies.

Data Sources

PubMed/MEDLINE, Embase, Cochrane/Central, Scopus, and Web of Science (through May 2023).

Study Selection

Randomized clinical trials and prospective cohort studies were eligible if they reported data on the diagnostic utility of prostate MRI in the setting of PCa screening.

Data Extraction

Number of screened individuals, biopsy indications, biopsies performed, clinically significant PCa (csPCa) defined as International Society of Urological Pathology (ISUP) grade 2 or higher, and insignificant (ISUP1) PCas detected were extracted.

Main Outcomes and Measures

The primary outcome was csPCa detection rate. Secondary outcomes included clinical insignificant PCa detection rate, biopsy indication rates, and the positive predictive value for the detection of csPCa.

Data Synthesis

The generalized mixed-effect approach with pooled odds ratios (ORs) and random-effect models was used to compare the MRI-based and PSA-only screening strategies. Separate analyses were performed based on the timing of MRI (primary/sequential after a PSA test) and cutoff (Prostate Imaging Reporting and Data System [PI-RADS] score ≥3 or ≥4) for biopsy indication.

Results

Data were synthesized from 80 114 men from 12 studies. Compared with standard PSA-based screening, the MRI pathway (sequential screening, PI-RADS score ≥3 cutoff for biopsy) was associated with higher odds of csPCa when tests results were positive (OR, 4.15; 95% CI, 2.93-5.88; P ≤ .001), decreased odds of biopsies (OR, 0.28; 95% CI, 0.22-0.36; P ≤ .001), and insignificant cancers detected (OR, 0.34; 95% CI, 0.23-0.49; P = .002) without significant differences in the detection of csPCa (OR, 1.02; 95% CI, 0.75-1.37; P = .86). Implementing a PI-RADS score of 4 or greater threshold for biopsy selection was associated with a further reduction in the odds of detecting insignificant PCa (OR, 0.23; 95% CI, 0.05-0.97; P = .048) and biopsies performed (OR, 0.19; 95% CI, 0.09-0.38; P = .01) without differences in csPCa detection (OR, 0.85; 95% CI, 0.49-1.45; P = .22).

Conclusion and relevance

The results of this systematic review and meta-analysis suggest that integrating MRI in PCa screening pathways is associated with a reduced number of unnecessary biopsies and overdiagnosis of insignificant PCa while maintaining csPCa detection as compared with PSA-only screening.

Population-based Organised Prostate Cancer Testing: Results from the First Invitation of 50-year-old Men

BACKGROUND

The European Union recently recommended evaluation of the feasibility of organised prostate cancer screening. In Sweden, regional population-based organised prostate cancer testing (OPT) programmes were introduced in 2020.

OBJECTIVE

To describe initial participation rates and diagnostic outcomes.

DESIGN, SETTING, AND PARTICIPANTS

The three most populated Swedish regions invited all men aged 50 yr to OPT by a letter in 2020-2022. Men with prostate-specific antigen (PSA) ≥3 ng/ml were referred for prostate magnetic resonance imaging (MRI). PSA assays differed across regions. Men with Prostate Imaging Reporting and Data System (PI-RADS) 1-3 and PSA density ≥0.15 ng/ml/cm3 or PI-RADS 4-5 were referred for a biopsy. Data were obtained from the Swedish Register for Organised Prostate Cancer Testing.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Overall and regional participation rates, PSA distributions, PI-RADS score distributions, cancer detection, and treatment were evaluated.

RESULTS AND LIMITATIONS

A total of 23 855 (35%) of 68 060 invited men participated; 696 (2.9%) had PSA ≥3 ng/ml, and of them, 306 (44%) had a biopsy indication and 221 (32%) had a biopsy. On biopsy, 93 (42%) had Gleason grade group ≥2 (0.39% of PSA-tested men) and 44 (20%) Gleason grade group 1 cancer. Most men with cancer had treatment with curative intent (70%) or were under active surveillance (28%). Across regions, proportions of men with PSA ≥3 ng/ml ranged from 2.3% to 4.0%, and those with PI-RADS score 4-5 ranged from 12% to 21%. A limitation is that results are applicable only to first testing of men in their early 50s.

CONCLUSIONS

The OPT programmes are feasible with good compliance to the diagnostic pathway. The use of MRI and PSA density avoided a biopsy for over half of the men with PSA ≥3 ng/ml. Inter-regional differences in diagnostic outcomes show a need for standardisation of the diagnostic pathway's components.

PATIENT SUMMARY

We report the diagnostic outcomes of inviting 68 000 50-yr-old men to organised prostate cancer testing.

Repeated Prostate Cancer Screening Using Prostate-Specific Antigen Testing and Magnetic Resonance Imaging: A Secondary Analysis of the STHLM3-MRI Randomized Clinical Trial

Importance

Magnetic resonance imaging (MRI) has been proposed to enhance the benefit-to-harm ratio of prostate cancer screening, but data on repeated screening outcomes are lacking.

Objective

To describe outcomes of prostate-specific antigen (PSA)-based screening with MRI and prostate biopsies at repeat screening.

Design, Setting, and Participants

This secondary analysis examined the population-based, screen-by-invitation STHLM3-MRI randomized clinical trial, which recruited Swedish men aged 50 to 74 years. Men were eligible for repeat screening at 2 to 3 years if they had PSA levels of 1.5 ng/mL or greater at trial inclusion, were randomized to the MRI-targeted group (including screening using biomarkers and MRI), and were not diagnosed with prostate cancer after the first screening round. Repeat screening was performed between November 10, 2021, and February 20, 2023. Data analysis was performed between May and August 2023.

Intervention

Participants underwent blood sampling, including PSA testing. A biparametric MRI scan was performed if PSA levels were 3 ng/mL or greater, and men with lesions with a Prostate Imaging-Reporting and Data System (PI-RADS) score of 3 or greater were referred for targeted and systematic biopsies.

Main Outcomes and Measures

The primary outcome was clinically significant prostate cancer (Gleason score of ≥3 + 4). Secondary outcomes included the proportion of men with clinically insignificant cancer (Gleason score of 6), the number of elevated PSA tests, MRI scans, and biopsy procedures.

Results

Of 7609 men from the first screening round, 2078 (27.3%) were eligible for and were invited for rescreening. Among the invitees, 1500 (72.2%) participated. Their median age was 67 (IQR, 61-72) years. Of 1094 men with PSA levels between 1.5 and 2.9 ng/mL in the first screening round, 326 (29.8%) had levels of 3 ng/mL or greater in the second round. Overall, 667 men (44.5%) had PSA levels of 3 ng/mL or greater: 617 underwent MRI (92.5%), revealing 51 (7.6%) with equivocal lesions (PI-RADS score of 3) and 33 (4.9%) with suspicious lesions (PI-RADS score of ≥4). Only 10 of 383 men (2.6%) with a prior negative MRI result had a lesion with a PI-RADS score of 4 or greater. Among the 1500 rescreened men, 48 (3.2%) had a Gleason score of 3 + 4 or greater, including 19 (1.3%) with a score of 4 + 3 or greater and 11 (0.7%) with a score of 6.

Conclusions and Relevance

In this secondary analysis of the STHLM3-MRI randomized clinical trial, cancer detection during the second screening round in biennial PSA and MRI-based prostate cancer screening was limited, and the detection of low-grade tumors remained low. A substantial proportion of men exhibited elevated PSA levels during rescreening, and a considerable portion of MRI scans performed lacked lesions suggestive of cancer. Future studies should explore strategies to reduce MRI-related resource use.

Trial Registration

ClinicalTrials.gov Identifier: NCT03377881.

Key learning on the promise and limitations of MRI in prostate cancer screening

MRI retains its ability to reduce the harm of prostate biopsies by decreasing biopsy rates and the detection of indolent cancers in population-based screening studies aiming to find clinically significant prostate cancers. Limitations of low positive predictive values and high reader variability in diagnostic performance require optimisations in patient selection, imaging protocols, interpretation standards, diagnostic thresholds, and biopsy methods. Improvements in diagnostic accuracy could come about through emerging technologies like risk calculators and polygenic risk scores to select men for MRI. Furthermore, artificial intelligence and workflow optimisations focused on streamlining the diagnostic pathway, quality control, and assurance measures will improve MRI variability. CLINICAL RELEVANCE STATEMENT: MRI significantly reduces harm in prostate cancer screening, lowering unnecessary biopsies and minimizing the overdiagnosis of indolent cancers. MRI maintains the effective detection of high-grade cancers, thus improving the overall benefit-to-harm ratio in population-based screenings with or without using serum prostate-specific antigen (PSA) for patient selection. KEY POINTS: • The use of MRI enables the harm reduction benefits seen in individual early cancer detection to be extended to both risk-stratified and non-stratified prostate cancer screening populations. • MRI limitations include a low positive predictive value and imperfect reader variability, which require standardising interpretations, biopsy methods, and integration into a quality diagnostic pathway. • Current evidence is based on one-time point use of MRI in screening; MRI effectiveness in multiple rounds of screening is not well-documented.

Prostate Age Gap: An MRI Surrogate Marker of Aging for Prostate Cancer Detection

BACKGROUND

Aging is the most important risk factor for prostate cancer (PC). Imaging techniques can be useful to measure age-related changes associated with the transition to diverse pathological states. However, biomarkers of aging from prostate magnetic resonance imaging (MRI) remain to be explored.

PURPOSE

To develop an aging biomarker from prostate MRI and to examine its relationship with clinically significant PC (csPC, Gleason score ≥7) risk occurrence.

STUDY TYPE

Retrospective.

POPULATION

Four hundred and sixty-eight (65.97 ± 6.91 years) biopsied males, contributing 7243 prostate MRI slices. A deep learning (DL) model was trained on 3223 MRI slices from 81 low-grade PC (Gleason score ≤6) and 131 negative patients, defined as non-csPC. The model was tested on 90 negative, 52 low-grade (142 non-csPC), and 114 csPC patients.

FIELD STRENGTH/SEQUENCE

3-T, axial T2-weighted spin sequence.

ASSESSMENT

Chronological age was defined as the age of the participant at the time of the visit. Prostate-specific antigen (PSA), prostate volume, Gleason, and Prostate Imaging-Reporting and Data System (PI-RADS) scores were also obtained. Manually annotated prostate masks were used to crop the MRI slices, and a DL model was trained with those from non-csPC patients to estimate the age of the patients. Following, we obtained the prostate age gap (PAG) on previously unseen csPC and non-csPC cropped MRI exams. PAG was defined as the estimated model age minus the patient's age. Finally, the relationship between PAG and csPC risk occurrence was assessed through an adjusted multivariate logistic regression by PSA levels, age, prostate volume, and PI-RADS ≥ 3 score.

STATISTICAL TESTS

T-test, Mann-Whitney U test, permutation test, receiver operating characteristics (ROC), area under the curve (AUC), and odds ratio (OR). A P value <0.05 was considered statistically significant.

RESULTS

After adjusting, there was a significant difference in the odds of csPC (OR = 3.78, 95% confidence interval [CI]: 2.32-6.16). Further, PAG showed a significantly larger bootstrapped AUC to discriminate between csPC and non-csPC than that of adjusted PI-RADS ≥ 3 (AUC = 0.981, 95% CI: 0.975-0.987).

DATA CONCLUSION

PAG may be associated with the risk of csPC and could outperform other PC risk factors.

LEVEL OF EVIDENCE

3 TECHNICAL EFFICACY: Stage 3.

Detection Rate of Prostate Cancer in Repeat Biopsy after an Initial Negative Magnetic Resonance Imaging/Ultrasound-Guided Biopsy

A negative multiparametric magnetic resonance imaging (mpMRI)-guided prostate biopsy in patients with suspected prostate cancer (PC) results in clinical uncertainty, as the biopsy can be false negative. The clinical challenge is to determine the optimal follow-up and to select patients who will benefit from repeat biopsy. In this study, we evaluated the rate of significant PC (sPC, Gleason score ≥7) and PC detection in patients who received a follow-up mpMRI/ultrasound-guided biopsy for persistent PC suspicion after a negative mpMRI/ultrasound-guided biopsy. We identified 58 patients at our institution that underwent repeat targeted biopsy in case of PI-RADS lesions and systematic saturation biopsy between 2014 and 2022. At the initial biopsy, the median age was 59 years, and the median prostate specific antigen level was 6.7 ng/mL. Repeat biopsy after a median of 18 months detected sPC in 3/58 (5%) patients and Gleason score 6 PC in 11/58 (19%). Among 19 patients with a downgraded PI-RADS score at the follow-up mpMRI, none had sPC. In conclusion, men with an initial negative mpMRI/ultrasound-guided biopsy had a high likelihood of not harboring sPC at repeat biopsy (95%). Due to the small size of the study, further research is recommended.

Therapy decisions after diagnosis of prostate cancer in men with negative prostate MRI

BACKGROUND

To investigate the clinical implications of magnetic resonance imaging (MRI) negative prostate cancer (PCa) in a cohort of men undergoing transperineal prostate biopsy.

METHODS

We included all men without prior diagnosis of PCa undergoing transperineal template saturation ± fusion-guided targeted biopsy of the prostate between November 2014 and March 2018. Before biopsy, all patients underwent MRI and biopsies were performed irrespective of imaging results. Baseline characteristics, imaging, biopsy results, and follow-up information were retrieved from the patient charts. Patients were classified as either MRI negative (Prostate Imaging Reporting and Data System [PIRADS] ≤ 2) or positive (PIRADS ≥ 3). ISUP grade group 1 was defined as clinically nonsignificant (nsPCa) and ≥2 as clinically significant PCa (csPCa). Primary outcome was the individual therapeutic decision after diagnosis of PCa stratified according to MRI visibility. Secondary outcomes were the sensitivity and specificity of MRI, and the urooncological outcomes after radical prostatectomy (RP).

RESULTS

From 515 patients undergoing prostate biopsy, 171 (33.2%) patients had a negative and 344 (66.8%) a positive MRI. Pathology review stratified for MRI negative and positive cases revealed nsPCa in 27 (15.8%) and 32 (9.3%) and csPCa in 26 (15.2%) and 194 (56.4%) of the patients, respectively. The rate of active treatment in the MRI negative was lower compared with the MRI positive cohort (12.3% vs. 53.2%; odd ratio [OR] = 0.12; p < 0.001). While men with negative MRI were more likely to undergo active surveillance (AS) than MRI positive patients (18.1% vs. 10.8%; OR = 1.84; p = 0.027), they rarely underwent RP (6.4% vs. 40.7%, OR = 0.10; p < 0.001). Logistic regression revealed that a negative MRI was independently protective for active treatment (OR = 0.32, p = 0.014). The specificity, sensitivity, negative, and positive predictive value of MRI for detection of csPCa were 49.2%, 88.2%, 56.4%, and 84.8%, respectively. The rate of adverse clinicopathological outcome features (pT3/4, ISUP ≥4, or prostate-specific antigen [PSA]-persistence) following RP was 4.7% for men with MRI negative compared to 17.4% for men with MRI positive PCa (OR = 3.1, p = 0.19).

CONCLUSION

Only few men with MRI negative PCa need active cancer treatment at the time of diagnosis, while the majority opts for AS. Omitting prostate biopsies and performing a follow-up MRI may be a safe alternative to reduce the number of unnecessary interventions.

Prostate Cancer Screening with PSA and MRI Followed by Targeted Biopsy Only

BACKGROUND

Screening for prostate cancer is burdened by a high rate of overdiagnosis. The most appropriate algorithm for population-based screening is unknown.

METHODS

We invited 37,887 men who were 50 to 60 years of age to undergo regular prostate-specific antigen (PSA) screening. Participants with a PSA level of 3 ng per milliliter or higher underwent magnetic resonance imaging (MRI) of the prostate; one third of the participants were randomly assigned to a reference group that underwent systematic biopsy as well as targeted biopsy of suspicious lesions shown on MRI. The remaining participants were assigned to the experimental group and underwent MRI-targeted biopsy only. The primary outcome was clinically insignificant prostate cancer, defined as a Gleason score of 3+3. The secondary outcome was clinically significant prostate cancer, defined as a Gleason score of at least 3+4. Safety was also assessed.

RESULTS

Of the men who were invited to undergo screening, 17,980 (47%) participated in the trial. A total of 66 of the 11,986 participants in the experimental group (0.6%) received a diagnosis of clinically insignificant prostate cancer, as compared with 72 of 5994 participants (1.2%) in the reference group, a difference of -0.7 percentage points (95% confidence interval [CI], -1.0 to -0.4; relative risk, 0.46; 95% CI, 0.33 to 0.64; P<0.001). The relative risk of clinically significant prostate cancer in the experimental group as compared with the reference group was 0.81 (95% CI, 0.60 to 1.1). Clinically significant cancer that was detected only by systematic biopsy was diagnosed in 10 participants in the reference group; all cases were of intermediate risk and involved mainly low-volume disease that was managed with active surveillance. Serious adverse events were rare (<0.1%) in the two groups.

CONCLUSIONS

The avoidance of systematic biopsy in favor of MRI-directed targeted biopsy for screening and early detection in persons with elevated PSA levels reduced the risk of overdiagnosis by half at the cost of delaying detection of intermediate-risk tumors in a small proportion of patients. (Funded by Karin and Christer Johansson's Foundation and others; GÖTEBORG-2 ISRCTN Registry number, ISRCTN94604465.).

Cost-effectiveness of Prostate Cancer Screening Using Magnetic Resonance Imaging or Standard Biopsy Based on the STHLM3-MRI Study

Importance

The combination of prostate-specific antigen (PSA) testing with magnetic resonance imaging (MRI) for prostate cancer detection has rarely been evaluated in a screening context. The STHLM3-MRI screening-by-invitation study (NCT03377881) has reported the benefits of using MRI with subsequent combined targeted and standard biopsies compared with using standard biopsies alone.

Objective

To investigate the cost-effectiveness of prostate cancer screening using MRI with combined targeted and standard biopsies compared with standard biopsies alone among men aged 55 to 69 years in Sweden, based on evidence from the STHLM3-MRI study.

Design, Setting, and Participants

This economic evaluation study was conducted from a lifetime health care perspective using a microsimulation model to evaluate no screening and screening strategies among adult men in Sweden. Men aged 55 to 69 years in Sweden were simulated for no screening and screening strategies. Input parameters were obtained from the STHLM3-MRI study and recent reviews. One-way and probabilistic sensitivity analyses were performed in May 2022.

Interventions

No screening, quadrennial PSA screening using standard biopsies alone, and MRI-based screening using combined targeted and standard biopsies.

Main Outcomes and Measures

The number of tests, incidence, deaths, costs, quality-adjusted life-years (QALY), and incremental cost-effectiveness ratios (ICERs) were estimated.

Results

A total 603 men were randomized to the standard arm, 165 of these participants (27.4%) did not undergo standard biopsy; 929 men were randomized to the experimental arm, 111 (11.9%) of whom did undergo MRI or any biopsy. Compared with no screening, the screening strategies were associated with reduced lifetime prostate cancer-related deaths by 6% to 9%. Screening with MRI and the combined biopsies resulted in an ICER of US $53 736, which is classified as a moderate cost per QALY gained in Sweden. Relative to screening with standard biopsies alone, MRI-based screening reduced the number of both lifetime biopsies and overdiagnosis by approximately 50% and had a high probability of being cost-effective than the traditional PSA screening.

Conclusions and Relevance

For prostate cancer screening, this economic evaluation study found that PSA testing followed by MRI with subsequent combined targeted and standard biopsies had a high probability to be more cost-effective compared with the traditional screening pathway using PSA and standard biopsy. MRI-based screening may be considered for early detection of prostate cancer in Sweden.

Prostate Cancer Detection Percentages of Repeat Biopsy in Patients with Positive Multiparametric Magnetic Resonance Imaging (Prostate Imaging Reporting and Data System/Likert 3-5) and Negative Initial Biopsy. A Mini Systematic Review

Multiparametric magnetic resonance imaging (mpMRI) has high sensitivity but low specificity for prostate cancer (PCa) diagnosis. The aim of our systematic review was to investigate the proportion of PCa found at a repeat biopsy in patients with a negative initial prostate biopsy, despite initial positive mpMRI. Included patients had a Prostate Imaging Reporting and Data System (PI-RADS)/Likert 3-5 lesion on mpMRI prior to the initial mpMRI-targeted prostate biopsy, which was negative for PCa on histology. The main outcomes were the overall and clinically significant PCa (csPCa; International Society of Urological Pathology >1 or any provided definition) percentages at a repeat biopsy. Out of 1179 articles identified, nine studies were included (a total of 485 patients). For patients with PI-RADS 3 lesions, overall and csPCa detection percentages ranged from 0% to 80% and from 0% to 20%, respectively, while for patients with PI-RADS ≥4 lesions, the corresponding percentages were 15.4-86% and 7.7-57%. An overall cancer detection percentage of 87.5% was reported in patients with Likert 5 lesions. Limitation of our review is the small number of studies and the protocol revision that allowed studies with <50 patients. In patients with a positive MRI result and a negative initial MRI-targeted biopsy, we suggest MRI re-reading and follow-up with repeat mpMRI or the standard repeat biopsy in cases at the highest risk. PATIENT SUMMARY: Literature has shown that in men with an abnormal prostate magnetic resonance imaging (MRI) scan but a normal biopsy, a significant prostate cancer can be present. MRI scans should be double checked, followed by standard checkups or repeat prostate biopsy, especially in highly suspicious cases.