Introduction
Prostate-specific membrane antigen (PSMA) radiation-guided surgery (PSMA-RGS) in patients with prostate cancer (PCa) have been reported in literature, but the feasibility of robot-assisted PSMA-RGS and the relevant evidence for identifying lymph node infiltration (LNI) are still insufficient. Recently, the interim analysis results of a phase II trial published in EUROPEAN UROLOGY, the top international urology journal, may provide preliminary evidence support. Yimaitong is compiled as follows.
Research Background
Expanded pelvic lymph node dissection (ePLND) is the gold standard for PCa lymph node staging diagnosis. In theory, PSMA-RGS can identify LNI in robot-assisted radical prostatectomy (RARP), avoiding unnecessary ePLND and overtreatment. The Italian research team described and analyzed the safety, feasibility and accuracy of PSMA-RGS identifying whether LIN is present in PCa patients during RARP.
Study Design
This phase II prospective study (NCT04832958) plans to include 100 medium- and high-risk PCa patients who have no evidence of lymph node or distant metastasis (cN0cM0) in routine imaging examinations. The patients plan to receive RARP+ePLND treatment, and their LNI risk is >5%. From June 2021 to March 2022, a total of 18 patients were included in the study, of which 12 were treated with PSMA-RGS (study cohort). All patients underwent 68Ga-PSMA positron emission tomography (PET)/ magnetic resonance imaging (MRI), and intravenously injected 99mTc-PSMA-IS the day before the operation, followed by single-photon emission computed tomography/computed tomography. Drop-In gamma probes were used for in vivo measurements, and all positive lesions (count rate ≥2 compared to background) were resected in parallel ePLND. The results were the patients' intraoperative and postoperative complications, perioperative results and performance characteristics of robot-assisted PSMA-RGS to identify LNI.
Figure 1 Research process
Study results
Among the 12 patients, 4 (33%), 6 (50%) and 2 (17%) were moderate-risk, high-risk and locally advanced PCa, respectively. Two (17%) patients had pathological lymph node uptake during 68Ga-PSMA-PET/MRI. The median surgical time, blood loss and hospitalization time of the patient were 230 min, 100 ml and 5 days, and no adverse events of and intraoperative complications occurred. One patient (8.3%) had complications of 30 days after surgery (Clavien-Dindo complications were graded 2).
3 patients (25%) had LNI at ePLND. The research team analyzed the samples of 96 lymph node areas one by one, and the results showed that the sensitivity, specificity, positive predictive values and negative predictive values of PSMA-RGS were 63%, 99%, 83% and 96%, respectively. At the patient level, the sensitivity, specificity, positive predictive values and negative predictive values of PSMA-RGS were 67%, 100%, 100%, and 90%, respectively.
Table 1 Diagnostic accuracy of samples of 96 lymph node areas
Table 2 Diagnostic accuracy of patients
Research conclusions
robot-assisted PSMA-RGS is a safe and feasible method that can be used for early recognition and staging of LNI in PCa patients. It has good specificity but poor sensitivity. There may be missed detection for micrometastatic lymph nodes.
References:
Gandaglia G, Mazzone E, Stabile A, et al. Prostate-specific membrane antigen Radioguided Surgery to Detect Nodal Metastases in Primary Prostate Cancer Patients Undergoing Robot-assisted Radical Prostatectomy and Extended Pelvic Lymph Node Dissection: Results of a Planned Interim Analysis of a Prospective Phase 2 Study. Eur Urol. 2022 Oct;82(4):411-418.
Edited by: Wang Mumu
Reviewed by: LR
Execution: Wang Mumu
