Abstract
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Objectives: C-11 Choline PET/CT is a validated tool for evaluation of biochemical recurrence (BCR) of prostate cancer (PCa) after definitive therapy. F-18 FDG PET/CT has widespread use for evaluation of multiple malignancies. The purpose of this study was to assess the incremental utility of FDG PET/CT in BCR patients who had received both a C-11 Choline and F-18 FDG PET/CT.
Methods: In this IRB-approved, HIPAA-compliant retrospective study, our institutional PET/CT database (01/2012 to 01/2016) was searched for all patients who underwent both C-11 Choline and F-18 FDG PET/CT within any 30-day period. One-hundred and seven separate patients and 190 exam pairs (both the C-11 Choline and F-18 FDG PET/CT) were identified. Incremental utility of FDG PET/CT was assessed based on a composite reference standard consisting of biopsy results, further work-up and/or follow-up.
Results: Seven (3.6%) F-18 FDG PET/CT exams in 3 patients (2.8%) were positive with a negative C-11 Choline PET/CT. All three patients had high grade Gleason 9 cancer at the time of initial diagnosis (of the 50 total patients in the cohort with a Gleason 9+ cancer), elevated Chromagranin A levels at the time of exam, and MRI demonstrating similar findings to those on F-18 FDG PET/CT collaborating findings of high grade disease. Fifty eight exams had negative findings on both C-11 Choline and F-18 FDG PET/CT, 90 were concordantly positive on both exams and 35 had positive findings on C-11 Choline but no positive findings on F-18 FDG PET/CT. Three patients with additional high grade features such as small cell or neuroendocrine prostate tumors were concordantly positive on both exams. Six PET/CT exams in 4 patients had diagnosed malignancies other than prostate cancer that had abnormal uptake on both C-11 Choline and F-18 FDG.
Conclusion: F-18 FDG PET/CT has limited value in the evaluation of BCR PCa especially in the setting of a positive C-11 Choline PET/CT, even in the setting of high grade Gleason 9 cancer. In rare circumstances if there is high suspicion for metastatic disease such as a rising PSA or elevated Chromagranin A in the setting of a negative C-11 Choline PET/CT, an F-18 FDG PET/CT could be considered in the setting of high grade (Gleason 9 or 10) PCa. Research Support: none $$graphic_E1790428-CFB8-463D-8748-1A38512648DC$$