TRUSting MRI.

Top Line:  Is a MRI-directed prostate cancer biopsy strategy non-inferior to standard biopsy in men undergoing standard population-based prostate cancer screening?

The Study: STHLM3 was a Swedish population-based non-inferiority trial that sought to determine if MRI followed by targeted and standard biopsy (if MRI positive) was non-inferior to standard 12-core biopsy at diagnosing clinically significant prostate cancer (grade group 2+). An important point here is that this was a true screening trial where men 50-74 were invited to participate and underwent standard PSA screening and Stockholm3 scoring. Stockholm3 is a model that predicts the risk of clinically significant prostate cancer on biopsy using clinical factors, blood biomarkers, and a polygenic risk score. Those with PSA of 3 or higher or a Stockholm3 risk of 11% or higher were randomized to standard biopsy or MRI. In the MRI arm, a PI-RADS score of 3 or higher was required to proceed to biopsy (unless the Stockholm3 score was 25% or higher). Nearly 2300 men (18% of those eligible) had indication for biopsy. In the standard group, 73% actually underwent biopsy compared to 36% in the MRI group. The rate of diagnosis of clinical significant cancer was 21% in the MRI arm compared to 18% in the standard arm, which was deemed non-inferior. In addition, MRI-guided biopsy resulted in significantly fewer insignificant prostate cancers (4% vs 12%) and fewer benign biopsies (11% vs 43%). Of note, when the MRI-guided arm was analyzed for targeted biopsy alone (no standard biopsy) the rate of diagnosis of clinically significant cancer was reduced from 21→ 17%, which was no longer non-inferior.

TBL: Among men with indication for prostate biopsy in the STHLM3 trial, the use of MRI halves the number of men who undergo biopsy while being non-inferior at diagnosing clinically significant prostate cancer when both MRI-targeted and standard biopsy are performed. | Eklund, N Engl J Med 2021