18F-PSMA PET/CT Versus 18F-NaF PET/CT for Staging and Treating Newly Diagnosed High-Risk Prostate Cancer: A Prospective Single-Center Study

Radiolabeled prostate-specific membrane antigen (PSMA) PET/CT has demonstrated superior diagnostic accuracy for staging prostate cancer (PC) compared with conventional imaging modalities. However, the clinical impact of replacing 18F-NaF PET/CT with PSMA PET/CT in high-risk PC remains underexplored. Methods: In this prospective single-center study, 160 patients with newly diagnosed high-risk PC underwent both 18F-NaF PET/CT and 18F-PSMA-1007 PET/CT within 3 wk. The 18F-PSMA PET/CT results were initially withheld; therefore, staging and treatment decisions were based solely on 18F-NaF PET/CT. At a later time point, the 18F-PSMA PET/CT findings were revealed, and staging and treatment plans were reassessed in a multidisciplinary research setting. Differences in staging and treatment intent were analyzed using Wilcoxon signed-rank tests. Results: The metastatic stage was reclassified for 40 patients (25%) after 18F-PSMA PET/CT, with 24% classified as having a more advanced stage and 1% having a less advanced stage (P < 0.001). Lymph node metastases accounted for most changes: 30 patients (19%) with no nodal involvement on CT were found to have nodal disease on 18F-PSMA PET/CT, and the rate of extrapelvic lymph node metastases increased from 16% to 27%. Treatment plans were changed for 21 patients (13%), primarily reflecting a shift from curative to noncurative intent or toward more intensified systemic therapy (P = 0.001). Conclusion: The use of 18F-PSMA PET/CT resulted in significant metastatic stage migration and influenced treatment planning in a substantial proportion of patients.