LAUSR

Prostate cancer has the second highest cancer incidence worldwide. Diagnosis of clinically significant prostate cancer (CSPC), defined as Gleason ≥3+4 or ≥ISUP 2, is underpinned by Prostate Imaging-Report and Data System (PI-RADS) scoring on MRI and serum PSA, with confirmation with prostate biopsy. Positive predictive value of PI-RADS 3 for CSPC is 13%. A PSA-density threshold of 0.15-0.18 ng/mL/cc is commonly utilised to justify biopsy vs PSA monitoring for PI-RADS 3. Retrospective analysis of MRI, PSA and pathology results for consecutive patients undergoing diagnostic investigations for prostate cancer between November 2021 and March 2022. Average age of 200 males was 66.4 (SEM 0.62). MRIs reported 6% ≤PI-RADS 2, 61.5% PI-RADS 3 and 32.5% ≥PI-RADS 4. Among the PI-RADS 3 (n=123), average prostate volume was 70.0cc (SEM 3.21) and PSA density was 0.12 (SEM 0.01). 17.9% PI-RADS 3 patients underwent prostate biopsy although just 8.9% had PSA-density >0.18 ng/mL/cc. 40.9% biopsies identified CSPC with average PSA-density 0.23 (SEM 0.06). Conversely, for the 59.1% biopsies with no cancer or non-CSPC, average PSA-density was 0.14 (SEM 0.03) (p 0.078). Almost 3/5 prostate biopsies carried out in patients with PI-RADS 3 lesions revealed non-CSPC or no cancer. There was a notable difference in PSA-density among PI-RADS 3 patients with biopsy-proven CSPC vs. non-CSPC or benign histology. Based on our institutions experience, we would propose a 0.2 ng/mL/cc PSA-density threshold when recommending biopsy over PSA monitoring for MRI reported PI-RADS 3 to improve patient selection for biopsy to identify CSPC.