PSMA PET/CT Accuracy in Diagnosing Prostate Cancer Nodes Metastases

Abstract

Background/aim: This study aimed to evaluate the diagnostic accuracy of prostate-specific membrane antigen (PSMA)-directed positron emission tomography/computed tomography (PET/CT) in pelvic nodal staging, using postoperative histopathology data as the reference standard.

Patients and methods: From January 2020 to June 2024, 78 patients with clinically significant prostate cancer (PCa) (ISUP Grade Group 2) underwent radical prostatectomy plus extended pelvic lymph node dissection (ePLND): 60 (77%) vs. 18 (23%) men had an intermediate vs. high risk PCa. All the patients underwent PSMA PET/TC before surgery for clinical staging and nodes focal uptake (standardized uptake value "SUVmax) was evaluated to rule out the presence of metastases.

Results: PSMA PET/CT was suspicious for nodes metastases in 16/78 (20.5%) men (median SUVmax 26.2), conversely, histology demonstrated nodes metastases in 18/78 (23.1%). PSMA PET/CT was negative for nodal involvement in all Grade Group 2 (GG2) PCa, positive in 4/4 (100%) GG3 PCa, and in 10/14 (71.4%) GG5 PCa. In detail, PSMA PET/CT was false negative in 2/4 PCa, characterized by GG5 plus ductal adenocarcinoma. Overall, PSMA PET/CT sensitivity, specificity, positive and negative predictive value, and diagnostic accuracy in diagnosing nodal metastases were equal to 87.5, 96.8, 87.5 96.7, and 92.3%, respectively.

Conclusion: PSMA PET/CT demonstrated an overall diagnostic accuracy of 92.3% in nodal staging (100% in GG2 PCa), which decreased to 63.6% in GG5 PCa. In high-risk patients or in case of ductal adenocarcinoma, a negative PSMA PET/CT does not rule out the need for ePLND.

Keywords: PSMA PET/CT; extended PNLD; nodes metastases; prostate cancer.