Primary Staging of Intermediate- and High-Risk Prostate Cancer Using [ ¹⁸ F]PSMA-1007 PET/CT and [ ¹⁸ F]NaF PET/CT: A Head-to-Head Comparison of Diagnostic Accuracy, Staging, and Patient Management

This study aimed to estimate the diagnostic accuracy and stage migration of [¹⁸F]PSMA-1007 PET/CT and its impact on patient management when compared with [¹⁸F]NaF PET/CT for primary staging of prostate cancer (PCa). <b>Methods:</b> In a substudy of the PRISMA-PET trial (EudraCT 2021-000123-12), patients with intermediate- and high-risk primary PCa were clinically staged using [¹⁸F]PSMA-1007 PET/CT with contrast-enhanced CT (ceCT). A masked [¹⁸F]NaF PET/CT was also performed for research purposes only. A research-focused multidisciplinary team (rMDT) conference was then conducted, beginning with the presentation of patient data. [¹⁸F]NaF PET/CT and ceCT results were presented, with masked results from the [¹⁸F]PSMA-1007 PET/CT, and stage and treatment decisions were made by consensus. Subsequently, the [¹⁸F]PSMA-1007 PET/CT results were reviewed, and the decisions were reconsidered. Final rMDT decisions, incorporating all imaging and available histology results, formed the composite reference standard. Diagnostic accuracy, stage migration, and treatment decision were compared. Treatment decisions made by the rMDT were compared with the clinical treatment decisions made. <b>Results:</b> In total, 128 men (median age, 72 y) were included in this study. Of these, 25 (19.5%) had intermediate-risk PCa and 103 (80.5%) had high-risk PCa. Our results revealed significantly higher accuracy in diagnosing lymph node metastases with [¹⁸F]PSMA-1007 PET/ceCT compared with ceCT with [¹⁸F]NaF PET/CT (<i>P</i> = 0.021). There was no significant difference for diagnosing bone metastases. Stage migration was observed in 22 patients (17%); 15 (12%) were upstaged and 7 (5%) downstaged. Treatment management changed for 18 patients (14%): 5 had altered curative strategy but the intent remained curative, 8 shifted from curative to life-prolonging treatment, 2 moved from life-prolonging to curative treatment, and 3 had adjustments within life-prolonging strategies. Forty patients received treatment that deviated from the rMDT decision. <b>Conclusion:</b> Staging PCa with [¹⁸F]PSMA-1007 PET/CT versus [¹⁸F]NaF PET/CT led to stage migration for 17% of patients and treatment management change for 14% of patients. Follow-up results from the PRISMA-PET trial will clarify the impact on patient outcomes.