For patients with prostate cancer who undergo a prostatectomy, a majority do not experience an increase in prostate-specific antigen (PSA). However, up to 40% of patients do have a rise in PSA levels. For patients with a biochemical recurrence of prostate cancer, conventional imaging such as magnetic resonance imaging, computed tomography (CT), and bone scans are the standard of care in disease localization and treatment planning. Salvage radiotherapy, with or without hormone therapy, is the treatment of choice for these patients, but about half will have PSA relapse. Inappropriate patient selection and nontargeted therapy is partially responsible for this high PSA failure rate. Conventional imaging adds to this due to a limited ability to define the location and extent of recurrent disease.
In an article published in the August 2021 edition of the Journal of Nuclear Medicine, Abiodun-Ojo and colleagues published the results of a prospective intent-to-treat clinical trial of the influence of 18F-fluciclovine positron emission tomography (PET)/CT findings on treatment management and radiation planning for patients with recurrent prostate cancer.1 18F-fluciclovine is a synthetic amino acid PET radiotracer with a high specificity for extra prostatic disease and is approved for the detection of recurrent prostate cancer with rising PSA. In this study, 165 participants with detectable PSA after they had prostatectomy were enrolled and randomized into 2 arms. In arm A, participants underwent conventional imaging prior to radiotherapy. Arm B participants underwent conventional imaging plus 18F-fluciclovine PET/CT before radiotherapy. Radiotherapy was planned to be offered to all participants at the beginning of the study with final decision on radiotherapy treatment and location of radiotherapy based on 18F-fluciclovine PET/CT findings.1
After 18F-fluciclovine PET/CT, 63 of the 79 patients in arm B had positive findings. Positive 18F-fluciclovine PET/CT findings were found in 53 patients who had negative conventional imaging findings. 18F-fluciclovine PET/CT had significantly higher positivity rates than conventional imaging for prostate bed, whole body, and pelvic lymph nodes.1 The whole-body positivity rate was 79.7% for 18F-fluciclovine PET/CT compared with 13.9% with conventional imaging (P <.001). Changes in radiotherapy decisions and fields were statistically significant, with 28 of the arm B patients having overall radiotherapy management changed after 18F-fluciclovine PET/CT. Conventional imaging findings were negative for 23 of the 28 patients having radiotherapy management changed. Four of these 28 patients had radiotherapy withdrawn due to detection of extra-pelvic disease. In 24 of the 75 patients continuing to undergo radiotherapy, the radiotherapy field was changed based on 18F-fluciclovine PET/CT findings. There was significant difference in mean PSA at the time of 18F-fluciclovine PET/CT between those patients with and without radiotherapy changes.
Abiodun-Ojo OA, Jani AB, Akintayo AA, et al. Salvage radiotherapy management decisions in postprostatectomy patients with recurrent prostate cancer based on 18F-fluciclovine PET/CT guidance. J Nucl Med. 2021;62:1089-1096.
