Impact of positive lymph nodes on robotic radical prostatectomy: medium-term oncological outcomes

To evaluate biochemical recurrence-free survival (BRFS), metastasis-free survival (MFS), cancer-specific survival (CSS), and the prognostic value of an undetectable postoperative prostate-specific antigen level (PSA < 0.1 ng/mL) in patients with lymph node-positive (pN1) prostate cancer after robot-assisted radical prostatectomy (RARP), for whom optimal management remains undefined. We retrospectively reviewed 1,689 patients who underwent RARP with standard or extended pelvic lymph node dissection (PLND) between March 2008 and March 2023 at a single institution; 37 were excluded for missing data, leaving 1,654 patients for analysis. Of 1,654 patients, 1,581 (95.6%) were pN0 and 73 (4.4%) were pN1. Extended PLND was performed in 15.3% of pN0 and 61.6% of pN1 patients; 9.6% of pN1 patients had ≥ 3 positive nodes. The 36-month BRFS was 71.9% (95% CI 68.9-74.8) for pN0 versus 32.0% (95% CI 19.2-44.6) for pN1 (p < 0.0001). The 5-year MFS was 92.5% (95% CI 90.5-94.5) versus 69.4% (95% CI 54.9-83.9), respectively; CSS did not differ significantly. Postoperative PSA was undetectable in 38 (52.1%) pN1 patients, of whom 29 (76.3%) later developed biochemical recurrence. On multivariate analysis, positive lymph nodes, ISUP grade > 2, and positive margins independently predicted recurrence; among pN1 patients alone, no variable reached significance, likely reflecting limited statistical power in this small subgroup rather than the absence of true associations. Lymph node metastases identified at RARP with PLND are associated with adverse oncological outcomes, reflecting more biologically aggressive disease. An undetectable postoperative PSA is associated with a more favorable course than persistent PSA, but confers limited negative predictive value, as most such patients eventually developed biochemical recurrence; persistent PSA should prompt early adjuvant therapy, whereas close surveillance may be considered as an initial strategy in selected low-risk pN1 patients with undetectable PSA.