Lymph Node Fluorescence During Robot-Assisted Radical Prostatectomy With Indocyanine Green: Prospective Dosing Analysis.

Abstract

To prospectively assess the ideal dosing and the value of fluorescent sentinel lymph node (LN) detection with indocyanine green (ICG) for the detection of LN metastases in intermediate- and high-risk patients undergoing robot-assisted prostatectomy and extended pelvic LN dissection (ePLND). Twenty patients received transperineal prostatic injections of ICG. Patients were cycled through 5 doses (1.25, 2.5, 3.75, 5, and 7.5 mg) so optimal ICG dosing could be discovered early. ICG injection was able to identify fluorescent LN (FLN) packets in all 20 patients. Compared to the higher ICG doses, the 1.25 and 2.5 mg doses had fewer FLN packets and were abandoned after 1 dose each. The median number of FLN packets was 4.0, 6.0, and 4.5 for the respective doses of 3.75, 5.0, and 7.5 mg. The external iliac group was the most common site of fluorescence in 27.2% of patients, followed by the common iliac (21.3%), obturator (20.3%), internal iliac (18.5%), and node of Cloquet (7.7%). Seven (35%) of 20 patients had node-positive disease. Of the 5 patients that had fluorescent tissue outside of our ePLND template, 1 had a positive node present in the anterior bladder neck fat. Across all patients, ICG had 62% sensitivity, 50% specificity, 8% positive predictive value, and 95% negative predictive value in detecting LN metastases. The low sensitivity of ICG for the detection of LN metastases highlights why FLN dissection with ICG does not represent an alternative to ePLND.