Safety and efficacy of salvage lymph node dissection in prostate cancer patients with nodal recurrence after radical prostatectomy: A prospective single center phase I/II study.

149 Background: Optimal management of pelvic nodal recurrence of prostate cancer after RP detected by PSMA-PET is still unclear, although a significant change in treatment due to early use of PET in the setting of BCR has been shown in multiple trials. As pelvic nodal recurrence can be seen as a “in between” state of disease before metastatic disease, metastasis directed therapy could improve oncological outcomes in the long term or at least delay the use of systemic treatment. Salvage Lymph node dissection (sLND) has been described in retrospective trials as effective with biochemical response in up to 60% of patients and long term BCR-free survival of up to 20%. Aim of this study was to prospectively evaluate safety as well as biochemical response to sLAE. Methods: In this study we prospectively included 71 patients with PET detected pelvic nodal recurrence after RP. Uptake in the prostatic fossa, previous pelvic radiation and short-term ADT were allowed. Patients with extra-pelvic metastasis, ECOG ≥2 or thromboembolic event within the last 6 months were excluded. Patients received complete bilateral open sLND. The resection margins were cranially the aortic bifurcation up to the level of the IMA, laterally the genitofemoral nerve, caudally the inguinal ligament or Cloquet's lymph node, medially the urinary bladder, and dorsally the pelvic wall. The obturator fossa was excised with exposure of the obturator nerve and removal of the presacral lymph nodes down to the periosteum. The primary endpoints of the study were safety measured by complication-rate and biochemical response to sLAE by PSA. Results: The median follow-up was 40 months. At the time of surgery median PSA was 1.20ng/ml (IQR 0.79-2.69) and the median number of positive spots on PET was 2 (IQR1-3). Overall, 30% patients showed biochemical remission defined as PSA <0.01. Within the follow up 90% (n=63) of patients experienced biochemical progression. The median time from sLND to BCR and additional treatments was 2 months (95%CI 2 – 5) and 12 months (95%CI 9 – 24) respectively. The median number of LNs removed was 39 and the most common site of relapse was the pelvis. Severe postoperative complications were rare yet did occur with 5 patients experiencing Clavien 3,4 and 5 complications of which one was a bilateral central pulmonary embolism which resulted in the death of the patient. Conclusions: Progression and additional treatments can be delayed with the use of sLAE, however long-lasting biochemical remission was rare. Certain patients with good initial PSA response were able to avoid systemic treatment. While mostly safe, severe side-effects did occur. Due to the potential complications of the surgery, it should be reserved for highly selected cases. Additional trials evaluating criteria for patient selection are important to further explore the potential benefit of sLAE. Clinical trial information: NCT02974075 .