A prospective trial of <sup>68</sup>Ga-PSMA and <sup>18</sup>F-FDG PET/CT in nonmetastatic prostate cancer patients with an early PSA progression during castration.
Beihe Wang, Chang Liu, Wei Yu, Jin Meng, Yingjian Zhang, Hualei Gan, Xiaoping Xu, Fangning Wan, Jian Pan, Xuejun Ma, Silong Hu, Stephen J. Freedland, Shaoli Song, Dingwei Ye, Yao Zhu
Abstract
e17579 Background: To evaluate tumor heterogeneity and burden in nonmetastatic prostate cancer patients with an early PSA progression during castration by 68 Ga-PSMA and 18 F-FDG PET/CT. Methods: The trial prospectively included 37 patients who had an early PSA progression (≤2ng/ml) during castration, and high-risk (PSADT ≤10 months) nonmetastatic disease by conventional imaging. All patients underwent both 68 Ga-PSMA and 18 F-FDG PET/CT. Lesions were classified into PSMA-dominant lesions (PSMA+/FDG- and PSMA+/FDG+) and PSMA-/FDG+ lesions according to the tracer uptake status. The primary endpoint was the prevalence of PSMA-/FDG+ disease. Results: All patients were treated with RP (median duration of castration = 23 months). The median PSA at imaging was 0.57ng/ml. Overall, 114 lesions were detected in 29 of the 37 patients. A high prevalence (73%) of N+/M+ disease was observed. Of the 114 lesions, 81 were PSMA-dominant and 33 were PSMA-/FDG+. Per patient level, 9 men (24%, 95%CI: 10%-39%) showed at least one new PSMA-/FDG+ lesions. A short PSADT ( P= 0.009, OR = 8.000) were associated with PSMA-dominant disease, while a high Gleason grade group ( P= 0.022, OR = 13.091) with PSMA-/FDG+ disease. 19 patients (51%) with 51 lesions could be enrolled for oligometastases-directed therapy including 10 PSMA-/FDG+ lesions. Among different disease stages, PSMA-/FDG+ disease was rarely detected in the hormone-sensitive cohort, but frequently found in the castration-resistant cohort. Conclusions: Using 68 Ga-PSMA and 18 F-FDG PET, we observed a high prevalence of N+/M+ disease and a significant proportion of PSMA-/FDG+ disease in patients with an early PSA progression during castration. (ChiCTR 1900022634). Clinical trial information: 1900022634 . [Table: see text]