Prognostic Factors of Castration‐Resistant Prostate Cancer Among Patients With Localized Prostate Cancer Who Underwent Robot‐Assisted Radical Prostatectomy in a Retrospective Multicenter Japanese Cohort ( MSUG94 )

ABSTRACT Objectives To explore clinicopathological risk factors associated with the development of castration‐resistant prostate cancer (CRPC) in patients who underwent robot‐assisted radical prostatectomy (RARP). Methods This study was conducted in nine Japanese institutions between 2012 and 2021. Patients with clinically metastatic PCa, those who received neoadjuvant or adjuvant therapy, were excluded. Consequently, 2825 patients with PCa were analyzed. Persistent prostate‐specific antigen (PSA) was determined as a level ≥ 0.2 ng/mL at 1 month postoperatively and consistently in subsequent measurements. Results Median follow‐up was 42.0 months. Under follow‐up, 493 (17.4%) and 25 (0.8%) patients progressed to biochemical recurrence and CRPC, respectively. One hundred and ninety‐six patients received salvage radiation therapy, and 229 patients received salvage androgen deprivation therapy. Among the 25 patients with CRPC, the median time to CRPC was 31.8 months. Univariate analysis revealed that preoperative PSA level, biopsy grade group (GG) 5, percentage of positive cancer cores, GG5 in RARP specimens, pT3b, pN1, positive surgical margins, lymphovascular invasion (LVI), and persistent PSA levels were associated with CRPC development. Multivariate analysis revealed that biopsy GG5 (adjusted hazard ratio aHR 12.74, p < 0.001), LVI (aHR 3.90, p = 0.011), and persistent PSA levels (aHR 8.66, p < 0.001) were independently associated with CRPC development. Furthermore, using these three factors made it possible to stratify CRPC‐free survival among patients with PCa who received RARP and confirmed external validation. Conclusions The combination of biopsy GG5, LVI, and persistent PSA levels may stratify the risk of developing CRPC in patients with PCa undergoing RARP.