PURPOSE To compare the diagnostic performance of the synthetic amino acid analogue positron emission tomography (PET) radiotracer anti-3-[18F]FACBC (fluciclovine) with computed tomography (CT) in the detection of recurrent prostate carcinoma. METHODS Retrospective analysis of 53 bone scan negative patients with suspected recurrent prostate carcinoma who underwent fluciclovine PET-CT and routine clinical CT within a 90-day interval. Correlation of imaging findings was made to histology and clinical follow-up. Positivity rates and diagnostic performance were calculated for fluciclovine PET-CT and CT. RESULTS 41/53 (77.4%) fluciclovine versus 10/53 (18.9 %) CT examinations had positive findings for recurrent disease. Positivity rates were higher with fluciclovine than CT at all prostate-specific antigen (PSA) levels, PSA doubling time (DT) and original Gleason scores (GS). Fluciclovine identified 27/51 and 9/41 more true positive patients than CT in the prostate/bed and in the extraprostatic regions, respectively. Of the 43 index lesions used to prove positivity, 42/43 (97.7%) had histologic proof verification. In 51/53 patients who had sufficient follow-up to calculate diagnostic performance in the prostate/bed, fluciclovine PET-CT demonstrated 88.6% sensitivity, 56.3% specificity, 78.4% accuracy, 81.6% positive predictive value (PPV), and 69.2% negative predictive value (NPV) compared with values of 11.4%, 87.5%, 35.3%, 66.7% and 31.1%, respectively on CT. For 41/53 patients with sufficient follow-up to calculate diagnostic performance for extraprostatic disease, fluciclovine PET-CT demonstrated 46.2% sensitivity, 100% specificity, 65.9% accuracy, 100% PPV, and 51.7% NPV compared with 11.5%, 100%, 43.9%, 100% and 39.5%, respectively on CT. CONCLUSION Fluciclovine PET-CT detects more patients with recurrent prostate cancer than CT and can better delineate prostatic from extraprostatic recurrence.

Purpose We explored the influence of FACBC (fluciclovine) positron emission tomography-computed tomography (PET-CT) on the decision to offer radiotherapy and radiotherapy treatment field recommendations in post-prostatectomy patients with recurrent prostate cancer. Materials and Methods Following institutional review board approval and informed consent, 87 patients with detectable prostate specific antigen (PSA) were recruited into a prospective clinical trial. Following an initial provider-determined radiotherapy plan based on conventional imaging, 44/87 patients were randomized to additionally undergo fluciclovine PET-CT. Pre- and post-fluciclovine radiotherapy decisions were compared and changes noted. Statistical significance of these decision changes was determined. Results 2/44 patients in the experimental arm dropped out before fluciclovine scanning. 34/42 (81.0%) had positive results on fluciclovine. Overall radiotherapy decision was changed in 17/42 (40.5%). Mean PSA, original Gleason score (GS), and prostatectomy-PET interval did not differ significantly between patients with and without radiotherapy decision changes. 2/42 (4.8%) had the decision for radiotherapy withdrawn due to positive extra-pelvic findings. Radiotherapy field decision was changed in 15/42 (35.7%). 11/15 (73.3%) had fields changed from prostate bed only to both prostate bed and pelvis, while 4/15 (26.7%) had fields changed from both prostate bed and pelvis to prostate bed only. Changes in overall radiotherapy decision and field were statistically significant (P<0.0001). However, the change in the decision to offer radiotherapy or not was not statistically significant (P=0.15). Conclusion Fluciclovine PET-CT significantly changed radiotherapy management decisions in post-prostatectomy patients with recurrent prostate cancer. Further work in determining differences in PSA free survival is ongoing.