18F-PSMA-1007 PET/CT Performance on Risk Stratification Discrimination and Distant Metastases Prediction in Newly Diagnosed Prostate Cancer

Abstract

Objective: To evaluate the prediction performance of ¹⁸F-PSMA-1007 PET/CT and clinicopathologic characteristics on prostate cancer (PCa) risk stratification and distant metastatic prediction.

Materials and methods: A retrospective analysis was performed on 101 consecutively patients with biopsy or radical prostatectomy proved PCa who underwent ¹⁸F-PSMA-1007 PET/CT. The semi-quantitative analysis provided minimum, maximum and mean standardized uptake (SUVmin, SUVmax and SUVmean) of PCa. Association between clinicopathologic characteristics (total prostate-specific antigen, tPSA and Gleason Score, GS) and PET/CT indexes were analyzed. The diagnostic performance of distant metastatic on PET/CT parameters, tPSA and GS was evaluated using logistic regression analyses. A path analysis was conducted to evaluate the mediating effect of tPSA level on the relation between semi-quantitative parameters of primary tumors and metastatic lesions.

Results: The PET/CT parameters were all higher in high risk stratification subgroups (tPSA>20 ng/mL, GS ≥ 8, and tPSA>20 ng/mL and/or GS ≥ 8, respectively) with high sensitivity (86.89%, 90.16% and 83.61%, respectively). The SUVmax, tPSA and GS could effectively predict distant metastatic with high sensitivity of SUVmax (90.50%) compared with tPSA (57.14%) and GS (55.61%). With a cutoff value of 29.01ng/mL for tPSA, the detection rate of distant metastasis between low and high prediction tPSA group had statistical differences (50.00% vs. 76.60%, respectively; P = 0.006) which was not found on guideline tPSA level (P>0.05). 6/15 (40%) patients tPSA between 20ng/mL to 29.01ng/mL without distant metastases may change the risk stratification. Finally, tPSA had a partial mediating effect on SUVmax of primary tumors and metastases lesions.

Conclusion: The ¹⁸F-PSMA-1007 PET/CT SUVmax has a higher sensitivity and can be an "imaging biomarker" for primary PCa risk stratification. The prediction tPSA level (29.01 ng/mL) is more conducive to the assessment of distant metastasis and avoid unnecessary biopsy.

Keywords: 18F-PSMA-1007 PET/CT; SUVmax; distant metastasis; primary prostate cancer; risk stratification; tPSA.

Figure 1

Flowchart of the PCa patient’s cohort.

Figure 2

In the first patient (A), ¹⁸F-PSMA-1007 PET/CT results show primary prostate cancer on whole-body maximum intensity projection (MIP) image (left). Axial PET image (right up) and axial fused image (right bottom) show primary tumor in the right prostate cancer lobe. In the second patient (B), ¹⁸F-PSMA-1007 PET/CT results show primary prostate cancer and tailbone metastasis on MIP image (left).

Figure 3

(A) Receiver operating characteristic (ROC) curve of the ¹⁸F-PSMA-1007 PET/CT indexes for prostate cancer risk stratification; (B) Receiver operating characteristic (ROC) curve of the ¹⁸F- PSMA-1007 PET/CT prostate cancer metastasis risk prediction.

Figure 4

Correlation between (A) tPSA level (tPSA high: >20 ng/mL vs tPSA low: ≤20 ng/mL), (B) Gleason Score (low-intermediate: <8 vs high: ≥8), (C) Prediction tPSA level (tPSA<29.01 ng/mL vs tPSA ≥ 29.01 ng/mL) and (D) Prediction SUVmax (SUVmax ≤ 13.76 vs SUVmax>13.76) for positive distant metastasis findings on 18F PSMA-1007 PET/CT. tPSA, total PSA; PCa, prostate cancer.

Figure 5

Comparison of ¹⁸F-PSMA-1007 SUVmax uptake in primary prostate tissue without metastasis (dark yellow violin box), primary prostate tissue with metastasis (pink violin box) and primary prostate cancer metastasis tissues (light yellow violin box) in tPSA ≤ 29.01 (A) and tPSA>29.01 (B) tPSA, total PSA; PCa, prostate cancer. ***P < 0.05, NS, No statistical difference.

Figure 6

Mediating effect model between primary prostate cancer SUVmax and Metastatic focis. tPSA, total PSA; PCa, prostate cancer.