Robotic Salvage Lymph Node Dissection in Recurrent Prostate Cancer: Lessons Learned from 68 Cases and Implications for Future Clinical Management

Purpose: Salvage lymph node dissection is a rescue treatment for patients with nodal recurrence after radical prostatectomy. Very limited data are available on robotic salvage lymph node dissection. Our purpose was to investigate perioperative and oncological outcomes of robotic salvage lymph node dissection in a large monocentric series. Materials and Methods: Perioperative data, complications within 30 days after surgery and oncological outcomes as assessed by histology, prostate specific antigen changes, prostate specific antigen nadir after salvage lymph node dissection, and time to further therapy were analyzed. To identify predictive factors for oncological outcome, Kaplan-Meier and Cox-regression analyses were performed. For cases with a mismatch between preoperative positron emission tomography/computed tomography and the number of histologically positive lymph nodes, prostate specific membrane antigen immunohistochemistry was performed on removed lymph nodes. Results: A total of 68 patients underwent robotic salvage lymph node dissection with a median operation time of 126 minutes, a blood loss of 50 ml, and a length of stay of 4 days. No major complications (>Clavien 3) occurred. Median followup was 12.1 months. Median time to further therapy was 12.4 months, 37% of patients experienced complete biochemical response (prostate specific antigen <0.2 ng/ml) and 11% reached an undetectable prostate specific antigen, which was maintained for >1 year in 3 cases. Lower preoperative prostate specific antigen, longer time between radical prostatectomy and salvage lymph node dissection, preoperative prostate specific membrane antigen positron emission tomography/computed tomography and complete biochemical response after salvage lymph node dissection were significant predictors of longer therapy-free survival (all p<0.005). Prostate specific membrane antigen immunohistochemistry revealed that prostate specific membrane antigen positron emission tomography/computed tomography tends to miss small lymph node metastases <5 mm. Conclusions: Robotic salvage lymph node dissection is a feasible approach with low perioperative morbidity and delays further systemic therapy in most patients. Prostate specific membrane antigen positron emission tomography/computed tomography detection is mostly limited to tumor foci >5 mm.