Could 68Ga-PSMA PET/CT Plus 18F-FDG PET/CT Be of Added Value in CRPC?

Patients with castration-resistant prostate cancer (CRPC) who have high Gleason score and prostate-specific antigen (PSA) may benefit from added 18F-FDG PET/CT in addition to 68Ga-PSMA PET/CT, according to a study published in The Journal of Nuclear Medicine.

“The 68Ga-PSMA PET/CT is a commonly used imaging modality in prostate cancers. However, few studies have compared the diagnostic efficiency between 68Ga-PSMA and 18F-FDG PET/CT and evaluated whether a heterogeneous metabolic phenotype (especially PSMA-FDG+ lesions) exists in patients with CRPC,” the researchers explained.

They retrospectively evaluated data on 56 patients with CRPC who underwent 68Ga-PSMA and 18F-FDG PET/CT, and stratified patients into two groups: those with PSMA-FDG+ lesions, and those without. They then assessed what risk factors might be associated with having at least one PSMA-FDG+ lesion.

68Ga-PSMA PET/CT, compared to 18F-FDG PET/CT, had a higher detection rate (75% vs 51.8%; P=0.004) and positive lesion number (135 vs 95), but 13 patients had at least one PSMA-FDG+ lesion. Patients with PSMA-FDG+ lesions had higher PSA and Gleason scores than those without lesions. Upon multivariate regression analysis, the Gleason score (≥8) and PSA (≥7.9 ng/mL) were correlated with detecting patients with PSMA-FDG+ lesions (P=0.01 and P=0.04, respectively).

“Gleason score and PSA are significant predictors for PSMA-FDG+ lesions, and CRPC patients with high Gleason score and PSA may benefit from additional 18F-FDG PET/CT,” the researchers concluded.