# Metastasis-Free Survival in Patients with Biochemical Recurrence After Robot-Assisted Radical Prostatectomy: A Multicenter, Retrospective Cohort Study in Japan (MSUG94 Group)

## TL;DR

This study found that lymphovascular invasion in prostate cancer surgical specimens predicts distant metastasis after biochemical recurrence in Japanese men.

## Contribution

Identified lymphovascular invasion as an independent predictor of metastasis after prostate cancer surgery in a Japanese cohort.

## Key findings

- 9% of patients with biochemical recurrence developed distant metastases.
- Lymphovascular invasion was a significant independent predictor of metastasis.
- Patients without lymphovascular invasion had better metastasis-free survival.

## Abstract

Prostate cancer is among the most prevalent cancers in men, with surgical removal of the prostate being the standard treatment. While PSA has been used as a marker for the possibility of subsequent cancer recurrence following surgery, cases exhibiting PSA recurrence do not consistently develop distant metastases. In this study, 491 Japanese men who experienced PSA recurrence after undergoing robot-assisted radical prostatectomy were observed over a period of five years. The study found that 9% of patients experienced distant metastasis. Multivariate analysis revealed that positive lymphovascular invasion by prostate cancer cells in the surgical specimen is an independent predictor of postoperative distant metastasis.

Robot-assisted radical prostatectomy (RARP) is the definitive surgical treatment for localized prostate cancer (PCa). Some patients with post-RARP biological recurrence (BCR) eventually develop distant metastases and subsequent PCa-related mortality. The objective of this study was to clarify the predictive factors for the risk of metastatic disease after BCR in patients with PCa who underwent RARP. This multicenter retrospective cohort study was conducted in nine Japanese institutions and enrolled 491 men with BCR, detected between 2011 and 2024. During the median 59-month follow-up period, 44 patients (9.0%) had radiological confirmation of distant metastasis. Patients with developed metastases after BCR exhibited higher biopsy Gleason grade and pathological T stage, increased lymphovascular invasion (LVI) in the surgical specimen, and a shorter interval from RARP to BCR. In univariate analysis, LVI and a time to BCR after RARP of ≤14.9 months were significant predictors of distant metastasis. In the multivariate analysis, LVI constituted a significant independent predictor of distant metastasis (p = 0.011). The 3-year metastasis-free survival (MFS) rates were 85.5% and 94.1% in patients with and without LVI, respectively. The MFS was significantly prolonged in patients with negative LVI compared to those with positive LVI (p = 0.007). In Japanese males with BCR after RARP, LVI was identified as an independent predictor of metastatic progression.