Abstract 352P
Background
High false positive rates in transitional zone (TZ) cases as PI-RADS v2.1 ≥3 may result in excessive targeted biopsies. This study focuses on the potential of the [-2]proPSA-related index to enhance the selection process for biopsy eligibility in patients with MRI TZ positivity.
Methods
From April 2022 to July 2023, 421 patients received transrectal prostate biopsy. First biopsies, systemic biopsies, and MRI-based cognitive target biopsies (MRITB) were conducted for those with PI-RADSv2.1 ≥3. 160 patients with proPSA-related indices were analyzed retrospectively. The indices include PSAD (PSA/ total prostate volume: TPV), PSATZD (PSA/ TZ volume: TZV), [-2] proPSA, phi, phiD (phi/TPV), phiTZD (phi/TZV), p2PSA/%f-PSA density ([-2]pro PSA/ freePSA*PSA/TPV), and p2PSA/%f-PSA TZD ([-2]pro PSA/ freePSA*PSA/TZV).
Results
Of the 160 patients assessed, 120 (75.0%) were diagnosed with cancer. Of these, 108 patients (90.0%) were diagnosed with Gleason score ≥ 7. The MRITB target sites were 80 cases in TZ, 108 cases in the peripheral zone (PZ), and 4 cases in the central zone (CZ). The positive rates of targeted biopsies were: TZ 36/100 cores (36.0%), PZ 98/148 cores (66.2%), and CZ 3/5 cores (60.0%). Notably, the positivity rate in TZ was significantly lower than that in PZ (P < 0.001). Additionally, the %[-2]proPSA-related index was analyzed in 49 TZ-targeted cases lacking MRI findings in the PZ or CZ. The AUCs for the cancer-positive predictive performance were as follows: p2PSA/%f-PSA TZD 0.8029, p2PSA/%f-PSA density 0.8011, phiD 0.7993, and [-2]proPSA 0.7933, with no significant differences among these indices. The p2PSA/%f-PSA TZD index, with the highest AUC and a cutoff value 2.75, reduced the number of biopsies by 16 (10.0%). Among these, 4 cases (1 with Gleason score 7 or higher) were positive for cancer, while all TZ-targeted biopsies were negative.
Conclusions
In this study, the predictive ability for TZ cancer was found to be highest with the p2PSA/%f-PSA TZD index. Moreover, this index may not only refine the selection of cases for biopsy but also provide a more precise determination of the necessity for a TZ-targeted biopsy.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
Nippon Medical School.
Funding
Initiative for Realizing Diversity in the Research Environment from MEXT, Japan.
Disclosure
All authors have declared no conflicts of interest.