There was increasing demand of MRI fusion prostate biopsy with MRI being more readily available and PIRADS 3 lesions commonly reported. The detection rate of clinically significant prostate cancer (csPCa) for the PIRADS 3 lesions varies and was only 6.6% in our local hospital. We would like to review whether PSA density (PSA-D) or RAPID (Rapid Access to Prostate Imaging and Diagnosis) risk score is a parameter for safely reducing the number of MRI fusion prostate biopsies in patients.

The demographic and biopsy results of patients who underwent MRI fusion prostate biopsy between March 2020 and Feb 2025 in the United Christian Hospital were retrospectively reviewed. CsPCa was defined as detection of any ISUP grade 2 (GS 3+4) or above disease. The basic 5-item RAPID risk score (age, history of biopsy, logPSA-D, prostate size, PIRADS score) was calculated using the online calculator provided. The negative predictive value (NPV) and the number of biopsies avoided were calculated.

219 patients with MRI fusion prostate biopsy performed within the study period were retrospectively reviewed. 67 patients were diagnosed with csPCa. Using PSA-D<0.15ng/ml as a cut off, 83 cases would have avoided a biopsy while 16 csPCa would be missed (NPV=84%). Using RAPID risk score <40% as threshold, 41 cases would have avoided a biopsy while 1 csPCa being missed (NPV=98%). Among the 76 patients having PIRADS 3 lesion, only 5(6.6%) were found with csPCa. Using PSA-D<0.15ng/ml, 37 patients would have avoided a biopsy while 1 csPCa being missed (NPV=97%). Using RAPID risk score <40%, 41 patients would have avoided a biopsy while 1 csPCa being missed (NPV=97%). Among the 82 patients having PIRADS 4 lesion, 27(32.9%) were found with csPCa. Using PSA-D<0.15ng/ml, 34 patients would have avoided a biopsy while 10 csPCa would be missed (NPV=77%). Using RAPID risk score <40%, 3 patients would have avoided a biopsy while no csPCa being missed (NPV=100%). Among the 61 patients having PIRADS 5 lesion, 35(57%) were found with csPCa. Using PSA-D<0.15ng/ml, 12 patients would have avoided a biopsy while 6 csPCa being missed (NPV=67%). Using RAPID risk score of <40%, neither any patients would have avoided a biopsy nor csPCa being missed.

Both PSA-D and RAPID risk score may serve as a risk stratification tool for PIRADS3 lesion to help reducing unnecessary biopsy. For higher grading PIRADS 4 or above lesions, RAPID risk score shows potential superior risk stratification with fewer csPCa being missed.