Role of Magnetic Resonance Imaging in Prostate Cancer Screening: A Pilot Study Within the Göteborg Randomised Screening Trial

Abstract

Background Magnetic resonance imaging (MRI) and targeted biopsies (TB) have shown potential to more accurately detect significant prostate cancer (PC) compared to prostate-specific antigen (PSA) and systematic biopsies (SB). Objective To compare sequential screening (PSA + MRI) with conventional PSA screening. Design, Setting and Participants Of 384 attendees in the 10th screening round of the Göteborg randomised screening trial, 124 men, median age 69.5, had a PSA of ≥1.8 ng/ml and underwent a prebiopsy MRI. Men with suspicious lesions on MRI and/or PSA ≥3.0 ng/ml were referred for biopsy. SB was performed blinded to MRI results and TB was performed in men with tumour-suspicious findings on MRI. Three screening strategies were compared (PSA≥3.0+SB; PSA≥3.0+MRI+TB and PSA≥1.8+MRI+TB). Outcome Measurements and Statistical Analysis Cancer detection rates, sensitivity and specificity were calculated per screening strategy and compared using McNemar´s test. Results and Limitations In total, 28 PC were detected, of which 20 were diagnosed in biopsy-naïve men. Both PSA≥3.0+MRI and PSA≥1.8+MRI significantly increased specificity compared with PSA≥3.0+SB (0.92 and 0.79 vs. 0.52; p<0.002 for both), while sensitivity was significantly higher for PSA≥1.8+MRI compared with PSA>=3.0+MRI (0.73 vs. 0.46, p=0.008). The detection rate of significant cancer was higher with PSA≥1.8+MRI compared to PSA≥3.0+SB (5.9 vs. 4.0%), while the detection rate of insignificant cancer was lowered by PSA≥3.0+MRI (0.3 vs. 1.2%). The primary limitation of this study is the small sample of men. Conclusion A screening strategy with a lowered PSA cut-off followed by TB in MRI-positive men seems to increase the detection of significant cancers while improving specificity. If replicated, these results may contribute to a paradigm shift in future screening. Patient Summary Major concerns in prostate-specific antigen screening are overdiagnosis and underdiagnosis. We evaluated whether prostate magnetic resonance imaging could improve the balance of benefits to harm in prostate cancer screening, and we found promising potential of using magnetic resonance imaging in addition to prostate-specific antigen.

What's new in screening in 2015?

“…As such, screening should only be started after the process of SDM and while there are many promising biomarkers the strength will be in combining those into risk prediction models including outcomes of multiparametric MRI. [16, 40]…”

“…[65] The model comprised protein biomarkers including PSA isoforms including some of those in the PHI[66] and the 4Kscore[67, 68], as well as MSMB, MIC1, 232 SNPs and clinical variables (age, family history, DRE, previous biopsy). Similar to the ERSPC and PCPT risk calculators[61], the PHI[66] and 4Kscore[68] as well as PSA followed by MRI in the Göteborg trial[16], the STHLM3 test improved the specificity, increased the predictive accuracy of finding GS 7 or higher (AUC 0.56, 95% CI 0.55–0.60 for PSA vs. 0.74, 95% CI 0.55–0.60 for the STHLM3 test) and reduced the number of unnecessary biopsies (by 32%, 95% CI 23–39). [65] While the authors are to be congratulated for carrying out a major screening study, which is certainly a step in the right direction, it is currently unknown whether the STHLM3 test really provides the so-needed major change in the balance of harms and benefit of PC screening.…”

“…MRI is also emerging as a potentially promising tool in the pre-diagnostic setting as well as to guide targeted biopsies. [16] We reviewed the literature to search for any major advances during 2015, above and beyond what is already known, that would increase our understanding of who, when and how often to screen for PC.…”

When no treatment is the best treatment: Active surveillance strategies for low risk prostate cancers

“…In summary, mpMRI could be useful in AS through (i) identifying men who would most benefit from additional biopsy (as presence of suspicious lesions on MRI predicts unfavorable histology [50]), (ii) increasing the diagnostic accuracy of prostate biopsy (as MRI-targeted biopsies in MRI-positive men increase the detection of significant cancers [51], outperform standard biopsies [52,53] and reduce misclassification [54]), (iii) reducing the number of biopsies needed to diagnose significant cancer [55] and the need for repeat biopsies [56] …”

Practical Barriers to Obtaining Pre-Biopsy Prostate MRI: Assessment in Over 1,500 Consecutive Men Undergoing Prostate Biopsy in a Single Urologic Practice

“…Also, novel systems have emerged for performing targeted biopsy of MRI-defined abnormalities [1,2]. As a result, urologists are increasingly interested in incorporating pre-biopsy prostate MRI into routine clinical practice [3], with a randomized screening trial suggesting the substantial benefit from such a practice [4]. …”