Value of Additional Systematic Cores During Magnetic Resonance Imaging-guided Targeted Biopsy in Prostate Cancer Screening for Young Men: Results from the PROBASE Trial.

[BACKGROUND AND OBJECTIVE] While magnetic resonance imaging (MRI)-guided targeted biopsy (TBx) is becoming an integral part of early detection of prostate cancer (PC), its role in screening of younger men remains unclear. We analyzed the additional value of systematic biopsy (SBx) in improving detection of clinically significant PC (csPC).

[METHODS] A total of 525 men aged 45-54 yr with confirmed prostate-specific antigen ≥3.0 ng/ml underwent multiparametric MRI followed by combined TBx and SBx between February 2014 and August 2023 within a multicenter prospective screening trial in Germany. Software-based MRI/ultrasound fusion TBx (2 cores per lesion) combined with SBx was performed via a transrectal or transperineal approach. The primary objective was to analyze differences in csPC detection rates between SBx and TBx in relation to MRI. Secondary objectives were detection rates by International Society of Urological Pathology grade group (GG) and the distribution of SBx and/or TBx findings.

[KEY FINDINGS AND LIMITATIONS] PC was detected in 209 men (39%), of which 148/209 cases were csPC (71%; GG ≥2). SBx missed 24/148 csPC cases (16%) and TBx missed 49/148 (33%). SBx detected 25 more low-risk PC cases than TBx (51 vs 26). For 64% of the cases in which SBx detected higher GG than TBx (n = 89, including GG 1), the positive cores were located within MRI-detected lesions. Five GG ≥3 PC cases were not identified on MRI. Limitations include the lack of centralized MRI review before biopsy, variability in biopsy technique, retrospective subgroup analysis, and short follow-up.

[CONCLUSIONS AND CLINICAL IMPLICATIONS] A relevant proportion of csPC cases were missed by two-core TBx, although they were correctly identified on MRI, suggesting limitations in targeting accuracy and/or the fusion technique. SBx cores or targeted perilesional sampling, particularly in young men with smaller prostate volume, might be a valuable complement to TBx to ensure reliable and early detection of (cs)PC in this age group.

[PATIENT SUMMARY] We looked at the effectiveness of systematic biopsy (usually 12 cores taken from the prostate gland) and targeted biopsy (cores from a suspicious area seen on a scan) of the prostate among men aged 45-54 years as part of a prostate cancer screening trial. The results show that using only two targeted cores per lesion seen on an MRI (magnetic resonance imaging) scan may miss a significant number of clinically relevant prostate cancers. One reason could be that MRI-targeted biopsies are not always perfectly accurate. To improve diagnostic accuracy in younger men, it may be necessary to take additional systematic tissue samples, or at least more samples from around any suspicious area. This trial is registered on ISRCTN as ISRCTN37591328.