A Prospective Trial of 68Ga-PSMA and 18F-FDG PET/CT in Nonmetastatic Prostate Cancer Patients with an Early PSA Progression During Castration

Abstract

◥Purpose: Tumor heterogeneity and burden, which impact treatment outcome in prostate cancer, are rarely evaluated using nextgeneration imaging.Experimental Design: The trial prospectively included 37 patients who had an early PSA progression (≤2 ng/mL) during castration and high-risk (PSA doubling time ≤10 months) nonmetastatic disease by conventional imaging. All patients underwent both 68 Ga-PSMA and 18 F-FDG PET/CT. Lesions were classified into PSMAþFDGAE lesions and PSMA-FDGþ lesions. The primary endpoint was the prevalence of PSMA-FDGþ disease. Tumor burden, predictors for positive imaging, and suitability for oligometastases-directed therapy (OMDT) were also evaluated.Results: All patients were treated with RP and the median duration of castration was 23 months. The median PSA at imaging was 0.57 ng/mL. Overall, 114 lesions were detected in 29 of the 37 patients. A high prevalence (73%) of Nþ/Mþ disease was observed. Of the 114 lesions, 81 were PSMAþFDGAE and 33 were PSMA-FDGþ. Per patient level, 9 men (24%; 95% confidence interval: 10%-39%) showed at least one new PSMA-FDGþ lesions. A short PSA doubling time (P ¼ 0.009, OR ¼ 8.000) was associated with PSMAþFDGAE disease, while a high Gleason grade group (P ¼ 0.022, OR ¼ 13.091) with PSMA-FDGþ disease. Nineteen patients (51%) with 51 lesions, including 10 PSMA-FDGþ lesions, could be enrolled for OMDT. Among different disease stages, PSMA-FDGþ 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 Nþ/Mþ disease and a significant proportion of PSMA-FDGþ disease in patients with an early PSA progression during castration (ChiCTR1900022634).

Prognostic implications of dual tracer PET/CT: PSMA ligand and [18F]FDG PET/CT in patients undergoing [177Lu]PSMA radioligand therapy

“…Our analysis showed that FDG+/PSMA− lesions occurred in one third (33%) of patients with mCRPC prior to RLT, which is in line with a recent study by Wang et al (33%) [19], and slightly higher compared to the results of Hofmann et al (19%) [14]. FDG+/PSMA− lesions were found in skeleton or liver in 44% of cases, which was comparable to prior results in the study of Thang et al (50% or 38%, respectively) [16].…”

Impact of the Noise Penalty Factor on Quantification in Bayesian Penalized Likelihood (Q.Clear) Reconstructions of 68Ga-PSMA PET/CT Scans

“…Before quantification of PSMA uptake can be used as a biomarker or surrogate endpoint to identify response to treatment, and before we can design sufficiently powered response evaluation studies, a thorough understanding of parameters affecting the quantitative results is required. Uptake of FDG and PSMA differ due to pharmacodynamical differences [ 8 , 9 , 10 ]. Therefore, comparison of uptake measurements from scans with different ligands should be approached with caution.…”

Solitary castrate-resistant prostate cancer metastasis to adrenal gland with concordant intense avidity on PSMA and FDG PET

“…While traditionally used to exclude other sites or sources of metastatic disease, FDGPET has improved disease characterisation in hormone-naïve PC and CRPC. 4 For CRPC, the addition of FDG PET after PSMA PET increased the detection of nodal or distant metastases from 65% to 73% in men with high risk CRPC and no metastasis on conventional imaging with CT and bone scan. Furthermore, patterns of PSMA and FDG PET uptake may inform eligibility for RLT 5 so FDG PET uptake may further assist with patient selection for MDT.…”