Abstract
1318
Background: When evaluating the initial diagnosed prostate cancer patients, there are partial PSMA-negative primary and metastatic lesions that cannot be ignored. The present study evaluated the potential value of 18F-FDG PET/CT in initial diagnosed prostate cancer patients compared with 68Ga-PSMA-11 PET/CT.
Methods: This retrospective study included 125 initial diagnosed prostate cancer patients who underwent 68Ga-PSMA-11 PET/CTand 18F-FDG PET/CT scans within 15 days. Lesions were divided into PSMA+/FDG+, PSMA+/FDG-, PSMA-/FDG+ and PSMA-/FDG-. Logistic regression analysis was performed to assess which factors were associated with the detection of 68Ga-PSMA-11 PET/CTand 18F-FDG PET/CT. Then, the clinicopathological characteristics of patients with PSMA-/FDG+ lesions and other patients were compared by univariate analysis and multivariate analysis. Detection rates on per-region and per-patient basis of 68Ga-PSMA-11 PETand 18F-FDG PET stratified by PSA (≤20, 20.0-≤100.0, >100.0ng/ml) were analysed.
Results: 25/125 (20.0%) patients showed at least one PSMA-/FDG+ lesion. 18/125 (14.40%) patients showed PSMA-/FDG+ in prostate lesions. We investigated 5/125 (4.0%) patients with PSMA-/FDG+ metastatic lymph nodes. PET/CT found PSMA-/FDG+ distant metastases in 4/125 (3.20%) patients. Multivariate analysis showed that PSA was an independent factor for predicting PSMA-/FDG+ lesions (95%CI=0.909-0.993, P=0.023). When PSA≤20ng/ml, the additional detection rate on a per-region basis of 18F-FDG PET was significantly higher than the 20.0<PSA≤100.0ng/ml group (20.34% vs 10%, P=0.026) and PSA>100.0ng/ml group (20.34% vs 4.35%, P=0.037). For per-patient level, when PSA≤20ng/ml, the additional value of 18F-FDG PET to assess T, N and M stages were 21.67% (13/60), 5.0% (3/60), and 3.33% (2/60), respectively. In general, when PSA≤20ng/ml, 18F-FDG PET could upgrade the clinical stage of 28.33% (17/60) of patients compared with 68Ga-PSMA-11 PET.
Conclusions: When 68Ga-PSMA-11 PET shows negative results for initial diagnosed prostate cancer patients, 18F-FDG PET may have potential additional value in some patients, especially those with low PSA (PSA≤20ng/ml).