Radiology Secrets Plus, Fourth Edition

1487 Objectives: There has been an increasing need for the development of a more specific and sensitive diagnostic probe to increase the detection of biochemical recurrence of prostate cancer (BCR PCa) before transformation into castrate resistant PCa (CRPC) and potentially metastatic CRPC. This need has motivated the development of a novel PET radiotracer, F-18-fluciclovine, which was approved by the FDA in 2016 for PCa patients with BCR after initial therapy. F-18-fluciclovine proved to be effective in altering management plans when conventional anatomical imaging fails to identify the site of disease [1]. With additional data, F-18-fluciclovine may be integrated in clinical algorithms for treatment planning in post-treatment biologically proven recurrent PCa. The aim of this study was to assess the diagnostic performance and impact on additional therapy plans in post-therapy PCa patients with rising PSA. Methods: In this retrospective data analysis, the patients were included if they met the criteria of >18 years old, history of PCa, received prior therapy (radical prostatectomy, local radiotherapy, brachytherapy) and found to have a rising PSA on consecutive measurements. Patients were excluded if there was no initial therapy (excluding initial staging scans), ongoing therapy or received prostate specific therapy within 3 months of imaging. The results of F-18-fluciclovine PET/CT were correlated with prior treatments, recent PSA levels, PSA velocity, findings on other imaging modalities, histopathological results and change in the management. Evaluation of the F-18-fluciclovine PET/CT was conducted blindly. The results of the scans were confirmed either by histopathology or follow-up data using PSA and imaging changes. The statistical analysis used a receiver-operator characteristic (ROC) curve was examined to assess the accuracy of fluciclovine relative to PSA. Sensitivity and specificity were calculated at a cutoff determined by maximizing the Youden index (J = sensitivity + specificity - 1). Results: This retrospective data analysis was conducted between January 2017 and October 2017, reviewing F-18-fluciclovine PET/CT post-therapy scans of 83 PCa patients with a rising PSA. Initially a total of 83 patients with a total of 86 F-18-fluciclovine scans were initially included in the study, with 3 patients having 2 scans within the study time. There were 8 patients excluded from further analysis; 7 due to no prior therapy (initial staging scan) and one currently receiving hormonal therapy. A final total of 75 patients were included with analysis of 78 scans. The study showed a detection rate of 71.8% (56/78). The ROC of the PSA was calculated from 70 of 78 patients with an optimal PSA cut-off of 1.41 ng/mL. The change in management with a positive scan was 83.9% (47/56). The patient demographics, detection rate, lesion demographics are listed in the table below. [asterisk]low rate of positivity is probably due to the small size and attendant sampling errors Conclusion: F-18-Fluciclovine showed improved performance of detecting biochemical recurrent prostate cancer when compared to other previously reported tracers. There was also significant impact on the management of patients with evidence of biochemical recurrent prostate cancer. REFERENCES: Akin-Akintayo OO, Jani AB, Odewole O et al. Change in Salvage Radiotherapy Management Based on Guidance With FACBC (Fluciclovine) PET/CT in Postprostatectomy Recurrent Prostate Cancer. Clinical Nuclear Medicine. 2017;42(1):322-e28.