Introduction:

Multiparametric MRI (mpMRI) is used in active surveillance (AS) for prostate cancer (PC) but has limited specificity. This prospective trial evaluated whether combining 18F-DCFPyL PSMA PET with mpMRI improves the detection of clinically significant PC (csPC) in patients on AS and reduces unnecessary biopsies prompted by false-positive mpMRI.

Methods:

In this IRB-approved, single-arm Phase II study, 95 patients on AS underwent PSMA PET and mpMRI on a dedicated PET/MRI scanner followed by systematic and targeted biopsies. PET and mpMRI were interpreted independently. The primary outcome was the diagnostic accuracy of mpMRI versus the combined PSMA PET/MRI for csPC.

Results:

Among 257 targeted lesions, the area under the curve (AUC) for combined PSMA PET/MRI was (0.77) compared to mpMRI alone (0.71) (p=0.2). PSMA PET/MRI showed improved sensitivity (63% vs. 28%) with a comparable negative predictive value (89% vs. 90%). Of 61 csPC lesions, 6 (9.8%) were uniquely identified by the combination. Nearly half of the biopsies for false-positive mpMRI or PET lesions (124/257; 48%) encompassing 17/95 (18%) of patients could have been avoided with combined imaging. Management changed in 8.4% of patients based on PET/MRI. The single health-system nature of the trial may limit the generalizability of our findings

Conclusion:

 Addition of PSMA PET to mpMRI with dedicated PET/MRI imaging enhances sensitivity in detecting csPC and may reduce the need for unnecessary biopsies in AS patients. Incorporating PSMA PET/MRI into clinical practice could refine surveillance protocols and support biopsy omission in select men with negative imaging.

Funding: This study was financially supported by the Duane and Dorothy Bluemke Foundation, the UW Carbone Cancer Center and the University of Wisconsin Prostate SPORE (NIH P50 CA269011).