Prospective Histopathologic Comparison Between [ 18 F]PSMA-1007 PET/CT and [ 18 F]Fluciclovine PET/CT of Intraprostatic Tumor Detection: The TRACER Study

Both [¹⁸F]PSMA-1007 PET/CT and [¹⁸F]fluciclovine PET/CT scans are commonly used for prostate cancer (PCa) staging. To the best of our knowledge, no head-to-head comparison of these 2 scans for detection of intraprostatic clinically significant PCa (csPCa) has been published. Methods: A multicenter prospective histopathologic validation study was conducted from October 2020 to February 2023. Patients with newly diagnosed biopsy-proven intermediate- or high-risk PCa scheduled for robot-assisted radical prostatectomy (RARP) were consecutively included. Before RARP, patients underwent both [¹⁸F]PSMA-1007 PET/CT as well as [¹⁸F]fluciclovine PET/CT. The diagnostic accuracy of [¹⁸F]PSMA-1007 PET/CT and [¹⁸F]fluciclovine PET/CT for intraprostatic PCa detection and localization was established by histopathologic examination of the prostate specimen as reference. Sensitivity, specificity, positive predictive value, and negative predictive value were compared. Results were based on per-lesion analysis and per-segment analysis. The focus was set on csPCa, defined as the International Society of Urological Pathology grade group 2 or higher. Results: In total, 77 patients were included of whom 57 underwent both PET/CT scans before RARP. Histopathology of the prostate specimen found a total of 88 lesions, of which 68 (77.3%) were qualified as csPCa. Using [¹⁸F]PSMA-1007 PET/CT, lesion-based sensitivity for csPCa was 86.8% (95% CI, 75.9%-93.4%), and with [¹⁸F]fluciclovine PET/CT, it was 73.5% (95% CI, 61.2%-83.2%). Sensitivity for segment-based csPCa localization was 46.6% (95% CI, 42.4%-50.8%) for [¹⁸F]PSMA-1007 PET/CT and 37.3% (95% CI, 33.3%-41.5%) for [¹⁸F]fluciclovine PET/CT. Whereas [¹⁸F]PSMA-1007 PET/CT has a significantly higher accuracy in the detection and localization of csPCa, [¹⁸F]fluciclovine PET/CT visualized all 5 non-[¹⁸F]PSMA-1007-avid index tumors. Conclusion: Compared with [¹⁸F]fluciclovine PET/CT, [¹⁸F]PSMA-1007 PET/CT demonstrated higher sensitivity for csPCa detection. However, in non-[¹⁸F]PSMA-1007-avid tumors, the [¹⁸F]fluciclovine PET/CT can visualize csPCa and has therefore a potential role in the diagnostic work-up and the clinical decision-making process.