Negative predictive value of PSMA PET scan for lymph node staging in patients undergoing robotic radical prostatectomy and pelvic lymph node dissection

PurposeTo assess the negative predictive value of PSMA PET scan for lymph node staging in patients undergoing robotic radical prostatectomy and pelvic lymph node dissection.Materials and methodsA retrospective analysis of patients who underwent robotic-assisted radical prostatectomy with pelvic lymph node dissection and had a preoperative negative PSMA PET scan for metastasis was performed. The documented pre-operative variables studied included age, BMI, PSA at diagnosis, Gleason score, and biopsy ISUP grades. Patients were categorised as low, intermediate and high risk according to the D Amico classification. The post-op variables included were number of lymph nodes harvested, number of positive nodes, positivity rate, size of the node metastasis, T staging and ISUP grading.ResultsThe overall negative predictive value of PSMA PET scan was 71.6%. Further sub-classification according to risk stratification demonstrated a NPV of 58.02%, 92.7% and 90% for high, intermediate and low risk, respectively.ConclusionPelvic lymph node dissection cannot be excluded based on a negative preop PSMA PET/CT scan.