Effect of Extended Pelvic Lymph Node Dissection on Oncologic Outcomes in Patients with D'Amico Intermediate and High Risk Prostate Cancer Treated with Radical Prostatectomy: A Multi-Institutional Study

Purpose: Pelvic lymph node dissection represents the gold standard of lymph node staging in patients with prostate cancer. We sought to assess the effect of extended pelvic lymph node dissection on oncologic outcomes in patients with characteristics of D'Amico intermediate or high risk prostate cancer treated with radical prostatectomy. Materials and Methods: In a multi-institutional database of 4 centers we identified 9,742 patients who underwent radical prostatectomy from 2000 to 2017 with or without pelvic lymph node dissection. Only patients with a greater than 5% probability of lymph node invasion according to the Briganti nomogram were included in study. We performed 2:1 propensity score matching to account for potential differences between the 2 cohorts. Cox regression models were used to test the effect of pelvic lymph node dissection on biochemical recurrence, metastasis and cancer specific mortality. Results: Overall 707 patients (7.3%) did not undergo pelvic lymph node dissection, of whom 520 and 187 harbored D'Amico intermediate and high risk characteristics, respectively. A median of 14 lymph nodes (IQR 8-21) were removed in the pelvic lymph node dissection cohort and 1,714 of these cases (19.0%) harbored lymph node metastasis. After propensity score matching the biochemical recurrence-free, metastasis-free and cancer specific mortality-free survival rates were 60.4% vs 65.6% (p = 0.07), 87.0% vs 90.0% (p=0.06) and 95.2% vs 96.4% (p = 0.2) for pelvic lymph node dissection vs no pelvic lymph node dissection 120 months after radical prostatectomy. Multivariable Cox regression models adjusted for postoperative and preoperative tumor characteristics revealed that pelvic lymph node dissection performed at radical prostatectomy was no independent predictor of biochemical recurrence, metastasis or cancer specific mortality (all p >= 0.1). Conclusions: There was no significant difference in oncologic outcomes in patients with D'Amico high or intermediate risk prostate cancer in whom pelvic lymph node dissection was or was not performed at radical prostatectomy. The therapeutic value of pelvic lymph node dissection remains unclear.