Background
Extended pelvic nodal dissection (ePLND) represents the gold standard for nodal staging in prostate cancer (PCa). Prostate-specific membrane antigen (PSMA) radioguided surgery (RGS) could identify lymph node invasion (LNI) during robot-assisted radical prostatectomy (RARP).
Objective
To report the planned interim analyses of a phase 2 prospective study (NCT04832958) aimed at describing PSMA-RGS during RARP.
Design, setting, and participants
A phase 2 trial aimed at enrolling 100 patients with intermediate- or high-risk cN0cM0 PCa at conventional imaging with a risk of LNI of >5% was conducted. Overall, 18 patients were enrolled between June 2021 and March 2022. Among them, 12 patients underwent PSMA-RGS and represented the study cohort.
Surgical procedure
All patients received 68Ga-PSMA positron emission tomography (PET)/magnetic resonance imaging; 99mTc-PSMA-I&S was synthesised and administered intravenously the day before surgery, followed by single-photon emission computed tomography/computed tomography. A Drop-In gamma probe was used for in vivo measurements. All positive lesions (count rate ≥2 compared with background) were excised and ePLND was performed.
Measurements
Side effects, perioperative outcomes, and performance characteristics of robot-assisted PSMA-RGS for LNI were measured.
Results and limitations
Overall, four (33%), six (50%), and two (17%) patients had intermediate-risk, high-risk, and locally advanced PCa. Overall, two (17%) patients had pathologic nodal uptake at PSMA PET. The median operative time, blood loss, and length of stay were 230 min, 100 ml, and 5 d, respectively. No adverse events and intraoperative complications were recorded. One patient experienced a 30-d complication (Clavien-Dindo 2; 8.3%). Overall, three (25%) patients had LNI at ePLND. At per-region analyses on 96 nodal areas, sensitivity, specificity, positive predictive value, and negative predictive value of PSMA-RGS were 63%, 99%, 83%, and 96%, respectively. On a per-patient level, sensitivity, specificity, positive predictive value, and negative predictive values of PSMA-RGS were 67%, 100%, 100%, and 90%, respectively.
Conclusions
Robot-assisted PSMA-RGS in primary staging is a safe and feasible procedure characterised by acceptable specificity but suboptimal sensitivity, missing micrometastatic nodal disease.
