Prognostic factors among patients with pathological Grade Group 5 prostate cancer based on robot-associated radical prostatectomy specimens from a large Japanese cohort (MSUG94)

Purpose: There are no definitive prognostic factors for patients with pathological Grade Group 5 (pGG 5) prostate cancer (PCa) undergoing robot-associated radical prostatectomy (RARP). This study aimed to explore the prognostic factors among patients with pGG 5 PCa in a large Japanese cohort (MSUG94). Methods: This retrospective, multi-institutional cohort study was conducted between 2012 and 2021 at ten centers in Japan and included 3195 patients. Patients with clinically metastatic PCa (cN1 or cM1) and those receiving neoadjuvant and/or adjuvant therapy were excluded. Finally, 217 patients with pGG5 PCa were analyzed. Results: The median follow-up period was 28.0 months. The 3- and 5-year biochemical recurrence-free survival (BCRFS) rates of the overall population were 66.1% and 57.7%, respectively. The optimal threshold value (47.2%) for the percentage of positive cancer cores (PPCC) with any GG by systematic biopsy was chosen based on receiver operating characteristic curve analysis. Univariate analysis revealed that the prostate-specific antigen level at diagnosis, pT, pN, positive surgical margins (PSMs), lymphovascular invasion, and PPCC were independent prognostic factors for BCRFS. A multivariate analysis revealed that PSMs and PPCC were independent prognostic factors for BCRFS. Using these two predictors, we stratified BCRFS, metastasis-free survival (MFS), and castration-resistant PCa-free survival (CRPC-FS) among patients with pGG 5 PCa. Conclusion: The combination of PSMs and PPCC may be an important predictor of BCRFS, MFS, and CRPC-FS in patients with pGG 5 PCa undergoing RARP.