Small-volume lymph node involvement and biochemical recurrence after robot-assisted radical prostatectomy with extended lymph node dissection in prostate cancer.

Background: We investigated prognostic factors for biochemical recurrence (BCR) after robot-assisted radical prostatectomy (RARP) with extended pelvic lymph node (LN) dissection.

Methods: We included 173 patients who underwent RARP with extended pelvic LN dissection without neoadjuvant therapy at our hospital between October 2010 and April 2018. BCR was defined as prostate serum antigen (PSA) levels ≥ 0.2 ng/mL; BCR-free survival rates were determined using Kaplan-Meier analysis. We used Cox regression analysis to evaluate effects of PSA and pathologic variables on BCR.

Results: Median follow-up was 27.9 (range 6.1-86.9) months. Five-year BCR-free survival was 89.5%. In multivariate analysis, positive LNs (HR 7.117; 95% CI 2.826-17.925; P < 0.001) and Gleason score (GS) ≥ 8 (HR 2.612; 95% CI 1.051-6.489; P = 0.039) were significant predictors of BCR. Patients with 1 or 2 positive LNs (n = 10) had significantly higher BCR-free survival rates than patients with ≥ 3 positive LNs (n = 5). We, therefore, stratified the patients as low-risk (GS < 8 and no positive LNs), intermediate-risk: (either GS ≥ 8 or positive LNs) and high-risk (both GS ≥ 8 and positive LNs). Their 1-year BCR-free survival rates were low-risk: 94.6%, intermediate-risk: 88.5%, and high-risk: 33.3% (P < 0.05).

Conclusions: Patients with 1-2 positive LNs and GS < 8 have low risk for BCR; close observation without immediate adjuvant hormonal therapy can be considered for these patients.