Clinical factors associated with biochemical recurrence of prostate cancer with seminal vesicle invasion followed by robot-assisted radical prostatectomy: a retrospective multicenter cohort study in Japan (the MSUG94 group).

Locally advanced prostate cancer (PCa) with pathological seminal vesicle invasion (pT3b) is a very-high-risk disease associated with biochemical recurrence (BCR), local recurrence, distant metastases, or mortality following definitive therapies. This study aimed to evaluate the risk factors associated with BCR following robot-assisted radical prostatectomy (RARP) in PCa patients with pT3b. A retrospective multicenter cohort study was conducted on 3,195 patients with PCa who underwent RARP at nine domestic centers between September 2011 and August 2021. Biochemical recurrence-free survival (BRFS) after RARP in PCa patients with pT3b was the primary end-point of the study. The secondary end-point was to determine the association between BCR and covariates. We enrolled 188 PCa patients with pT3b. The median follow-up period was 32.8 months. At the end of the follow-up period, 76 patients (40.4%) developed BCR, of whom 15 (8.0%) were BCR at the date of surgery. The 1-, 2-, and 3-year BRFS rates were 76.4, 65.9, and 50.8%, respectively. Multivariate analysis identified initial prostate-specific antigen level and positive surgical margins (PSM) as significant predictors of BCR in PCa patients with pT3b undergoing RARP. In this study, we investigated the BRFS in PCa patients with pT3b. As PSM was an independent predictor of BCR in PCa patients with pT3b, these patients may require a combination of therapies to improve the BCR.