Undetectable PSA after radical prostatectomy is more likely in low burden N+ prostate cancer patients when an extended lymph node dissection is performed

Objectives: To analyze the likelihood of undetectable PSA (< 0.01 ng/mL) after extended (ePLND) versus standard pelvic lymph-nodes dissection (sPLND) in pN+ patients. Materials and methods: The institutional prospectively maintained Prostate Cancer Database was queried for patients who underwent radical prostatectomy with PLND and were found with 3or less lymph-nodal metastases between 2007 and 2017. The extension of the PLND was defined according to the number of lymph-nodes (LN) removed. Patients in the 75th or higher percentile of lymph-nodes removed were considered as the ePLND group; patients in the 25th or lower percentile in the sPLND group. Groups were compared in clinical and pathological variables. Student T-test was used for comparing continuous variables; chi-square test was used for categorical variables. Multivariable logistic regression assessed the probability of undetectable PSA at 3rd month postoperatively. Kaplan-Meier method estimated the probability of biochemical recurrence. Differences between the groups were compared by Log-rank test. Results: 1478 patients were treated within the time span considered. 95 with 1 to 3 lymph-nodal metastases were extracted. After accounting for inclusion criteria, 23 patients with a median of 11 LN removed were included in the sPLND group (25th percentile); 23 patients with > 27 LN were included in ePLND group (75th percentile). Surgical time was longer for ePLND. Sixteen patients (69.6%) who underwent ePLND had undetectable PSA postoperatively. At multivariable analysis, the probability of undetectable PSA at 3rd month was higher in patients who received an ePLND (HR=5.18; IC 95%=1.16-23.11; P=.03). Conclusions: ePLND is more likely to predict undetectable PSA at third month after radical prostatectomy, irrespective of disease characteristics.