CRPC patients with a high Gleason score (≥ 8) and a high PSA (≥ 7.9 ng/mL) may benefit from [18F]FDG PET/CT. For staging, the addition of [18F]FDG PET/CT could increase the detection rate of local recurrence, lymph node metastasis, distant metastasis, and any location from 14.3 to 19.6%, from 42.9 to 55.4%, from 35.7 to 39.3%, and from 75.0 to 85.7%, respectively, when compared with [68Ga]Ga-PSMA PET/CT alone. This evidence concerns the gene KLK3 and metastatic malignant neoplasm in the lymph nodes.