A Multicentre Clinical Trial Evaluating a Drop-in Gamma Probe for Minimally Invasive Sentinel Lymph Node Dissection in Prostate Cancer

Background: This study evaluated the safety and performance of a drop-in gamma probe for prostate cancer (PCa) sentinel lymph node biopsy (SeLNB) in a prospective, open-label, multicentre, single-arm clinical trial.

Objective: The main objective was to determine the sentinel lymph node (SeLN) detection rate with the drop-in gamma probe system. The secondary objectives were overall performance and safety.

Design, setting, and participants: At three European centres, patients received an ultrasound-guided systemic and tumour-targeted injection of [^99mTc]Tc-nanocolloid followed by planar lymphoscintigraphy and/or single-photon emission computerised tomography. The next day, manual laparoscopic or robot-assisted radical prostatectomy was performed, including SeLN dissection (SeLND) and extended pelvic lymph node dissection (ePLND).

Outcome measurements and statistical analysis: SeLNs were detected with the drop-in probe and a rigid laparoscopic gamma probe (RLGP). The primary endpoint of the study was the SeLND rate defined as the percentage of patients with at least one SeLN detected in vivo by the drop-in probe. The secondary endpoints included diagnostic performance, ease of SeLN detection, number of SeLNs detected, and safety. The first two patients at each site (six in total) were used for familiarisation.

Results and limitations: A total of 27 patients were included in the main analysis. SENSEI successfully detected at least one SeLN in all 27 patients, resulting in a detection rate of 100% (95% confidence interval 87.2-100%). The total number of SeLNs identified with SENSEI was 85 (median three SeLNs per patient, range 1-6); of these 85 SeLNs, 12 were located outside of the ePLND template. In the nine patients in whom the RLGP was used, SENSEI detected two SeLNs that could not be detected with the RLGP due to manoeuvrability restrictions. Ten of the 27 patients were pN1; four patients had a false-negative SeLNB. No adverse events or complications were related to the use of the drop-in probe.

Conclusions: The study demonstrated that the drop-in gamma probe meets the performance and safety requirements for SeLNB in PCa. The device provided improved manoeuvrability and SeLN detection compared with the conventional RLGP.

Patient summary: A novel device was tested for detecting sentinel lymph nodes during minimally invasive surgery for prostate cancer. In this first evaluation, the performance and safety of the device were evaluated positively.