The utility of Ga-PSMA PET/CT guided salavge pelvic lymph node dissection in men with biochemical recurrence after radical prostatectomy.

Abstract

Introduction/Background: The success of salvage therapy in biochemical recurrence (BCR) following radical prostatectomy (RP) is dependent on the quality of staging imaging employed. 68Ga-PSMA PET/CT shows promise for the assessment of recurrence following RP. We aimed to assess the utility of salvage pelvic lymph node dissection (sPLND) in men with BCR after RP selected by 68Ga-PSMA PET/CT. Methods: From July 2014 to October 2015 men with BCR after RP demonstrating evidence of retroperitoneal or pelvic nodal disease recurrence on 68Ga-PSMA PET/CT treated with sPLND were retrospectively selected for this analysis. BCR was defined as postop PSA of 0.2 ng/ml or rising PSA below this level if leading to the use of salvage therapy. Biochemical response was defined as PSA <0.2 ng/ml at 6 weeks after sPLND. Results: From 296 68Ga-PSMA PET/CT performed at our centre, fourteen men our inclusion criteria. The median PSA at the time of PSMA PET/CT was 2.1 (IQR 0.46-3.60) ng/ml with median time between prostatectomy and PSMA PET/CT of 7 (IQR 2-11) years. The median number of avid lymph nodes was 1(IQR 1-3). The median nodal yield was 13(IQR 15-22) with 3(IQR 1-4) nodes being positive for metastatic disease. The median post procedure PSA was 1.39 (IQR 0.29-4.31) ng /ml with one man experiencing biochemical response. Conclusions: Despite previous suggested therapeutic utility of sPLND in BCR after RP selected by nodal pathologic uptake on PET/CT scan, our experience with such men selected by 68Ga-PSMA PET/ CT findings has been less encouraging. It is prudent to conclude that the availability of PSMA PET does not warrant omitting PLND in high-risk patients at the time of surgery with a view to perform sPLND in PSMA PET/CT positive patients.