68Ga-PSMA PET/CT for the evaluation of metastasis in patients with prostate cancer: A systematic review and meta-analysis.

Objective: The aim of this study was to assess the diagnostic value of gallium-68-prostate specific membrane antigen (⁶⁸Ga-PSMA) positron emission tomography/computed tomography (PET/CT) in detecting metastases in prostate cancer (PCa) patients.

Materials and methods: A comprehensive literature search of studies published before August 2021 in PubMed, Embase and Cochrane Library databases was conducted.The methodological quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 tool. Studies investigating the diagnostic value of ⁶⁸Ga-PSMA PET/CT were selected for qualitative and quantitative analysis.

Results: Twenty-five articles using ⁶⁸Ga-PSMA PET/CT for detecting metastases in PCa patients were selected for qualitative analysis, 16 of which were selected for meta-analysis. The sensitivities of ⁶⁸Ga-PSMA PET/CT in detecting lymph node metastases ranged from 33.3% to 96.08%, with high specificities ranged from 82% to 100%. Gallium-68-PSMA PET/CT demonstrated outstanding diagnostic performance in PCa patients with bone metastases. Only two articles about ⁶⁸Ga-PSMA PET/CT for lung metastases showed that the detection value was limited. It was difficult to distinguish lung metastases in PCa patients from benign lesions or primary lung cancer. There was only one article about ⁶⁸Ga-PSMA PET/CT for liver metastases, which showed that about 77.7% of metastatic lesions will be ⁶⁸Ga-PSMA-positive and 22.3% will be false negatives. Due to the lack of articles on PCa visceral metastases, we only conducted a meta-analysis on lymph node metastases and bone metastases. In our meta-analysis, the per-patient pooled sensitivity, specificity, positive likelihood ratio (LR⁺), negative likelihood ratio (LR^-), diagnostic odds ratio (DOR), and the area under the ROC curve (AUC) of lymph node metastases were 0.61, 0.96, 14.4, 0.41, 35, and 0.95, respectively. The per-lesion pooled sensitivity, specificity, LR⁺, LR^-, DOR, and AUC of V were 0.74, 0.99, 76.0, 0.26, 289 and 0.99, respectively. The per-patient pooled sensitivity, specificity, LR⁺, LR^-, DOR, and AUC of bone metastases were 0.97, 1.00, 1100.1, 0.03, 37490 and 0.98, respectively.

Conclusion: Gallium-68-PSMA PET/CT demonstrated outstanding diagnostic performance for bone metastases in PCa patients. The majority of lymph node metastases, lung metastases, and liver metastases overexpressed PSMA, which could be directly detected. However, a considerable number of lesions were false negatives.