Change in Salvage Radiotherapy Management Based on Guidance With FACBC (Fluciclovine) PET/CT in Postprostatectomy Recurrent Prostate Cancer

We explored the influence of FACBC (fluciclovine) PET/CT on the decision to offer radiotherapy and radiotherapy treatment field recommendations in postprostatectomy patients with recurrent prostate cancer.After obtaining institutional review board approval and informed consent, 87 patients with detectable prostate-specific antigen (PSA) levels were recruited into a prospective clinical trial. After an initial provider-determined radiotherapy plan based on conventional imaging, 44 of 87 patients were randomized to additionally undergo fluciclovine PET/CT. Pre- and post-fluciclovine radiotherapy decisions were compared and changes were noted. Statistical significance of these decision changes was determined.Two of 44 patients in the experimental arm dropped out before fluciclovine scanning. Thirty-four (81.0%) of 42 had positive results on fluciclovine. Overall radiotherapy decision was changed in 17 (40.5%) of 42. Mean PSA, original Gleason score, and prostatectomy-PET interval did not differ significantly between patients with and without radiotherapy decision changes. Two (4.8%) of 42 had the decision for radiotherapy withdrawn due to positive extrapelvic findings. Radiotherapy field decision was changed in 15 (35.7%) of 42. Eleven (73.3%) of 15 had fields changed from prostate bed only to both prostate bed and pelvis, while 4 (26.7%) of 15 had fields changed from both prostate bed and pelvis to prostate bed only. Changes in overall radiotherapy decision and field were statistically significant (P0.0001). However, the change in the decision to offer radiotherapy or not was not statistically significant (P = 0.15).Fluciclovine PET/CT significantly changed radiotherapy management decisions in postprostatectomy patients with recurrent prostate cancer. Further work in determining differences in PSA-free survival is ongoing.