To explore the value of ⁶⁸Ga-prostate specific membrane antigen (PSMA)-11 PET/CT in newly diagnosed prostate cancer patients with different risk stratifications, and to compare the performance of this modality with conventional imaging in detecting metastases.

From June 2019 to July 2020, the clinical and imaging data of 60 patients (age range: 44-88 years, median age 69 years) who underwent ⁶⁸Ga-PSMA-11 PET/CT imaging in Fudan University Shanghai Cancer Center were retrospectively analyzed. Spearman rank correlation analysis was used to explore the correlation of SUV_max in primary foci with prostate specific antigen (PSA) and Gleason score (GS). Based on the D′Amico risk stratification (PSA>20 μg/L and ≤20 μg/L, GS>7 and ≤7), the detection rates of ⁶⁸Ga-PSMA-11 PET/CT for metastases were evaluated by χ² test, and the differences of SUV_max were analyzed by Mann-Whitney U test. Patients were divided into high-risk (PSA>20 μg/L and GS>7), medium-risk (PSA>20 μg/L and GS≤7, or PSA≤20 μg/L and GS>7), and low-risk (PSA<20 μg/L and GS<7) groups according to PSA levels and GS. Compared with conventional imaging (bone imaging, CT or MRI), the ability of ⁶⁸Ga-PSMA-11 PET/CT to detect metastatic tumors, and the utility to change the prostate cancer stage were evaluated by Fisher′s exact test.

High uptake of ⁶⁸Ga-PSMA-11 was observed in primary lesions of 60 patients, and SUV_max was positively correlated with GS or PSA (r_s values: 0.42, 0.38; P values: 0.001, 0.002). The detection rates of lymph node and bone metastases in the group with PSA>20 μg/L were 11/18 and 13/18, respectively, which were higher than those in the group with PSA≤20 μg/L (28.57%(12/42) and 35.71%(15/42); χ² values: 6.56, 7.56, P values: 0.010, 0.006. However, there was no statistical significance in the SUV_max of these lesions(z values: -1.04, -0.96; P values: 0.299, 0.337). There was a statistical difference in the detection rates of lymph node and bone metastases between the group with GS>7 and the group with GS≤7 (lymph node: 54.05%(20/37) vs 13.04%(3/23), χ²=10.09, P=0.001; bone metastases: 59.46%(22/37) vs 26.09%(6/23), χ²=8.19, P=0.004), as well as the SUV_max of bone metastases(z=-2.02, P=0.044). In the high-risk group, ⁶⁸Ga-PSMA-11 PET/CT had the higher detection rate of metastases than conventional imaging (16/17 vs 10/17; P=0.039) and it changed 25.0%(15/60) of the patients′ staging.

PSA and GS affect the detection rate of ⁶⁸Ga-PSMA-11 PET/CT. In patients with high-risk prostate cancer, ⁶⁸Ga-PSMA-11 PET/CT is superior to conventional imaging in detecting metastases. When PSA>20 μg/L and GS>7, it is better to use ⁶⁸Ga-PSMA-11 PET/CT in prostate cancer staging.

Prostatic neoplasms; Prostate-specific membrane antigen; Isotope labeling; Gallium radioisotopes; Positron-emission tomography; Tomography, X-ray computed