There is a discrepancy in guideline recommendations regarding prostate cancer detection; National Comprehensive Cancer Network (NCCN) guidelines recommend using 18F-fluciclovine PET-CT for prostate cancer biochemical recurrence localization after radical prostatectomy as opposed to European Association of Urology (EAU) guidelines, which recommend prostate-specific membrane antigen (PSMA) PET-CT. Jeremie Calais, MD, Johannes Czernin, MD, and colleagues compared using 18F-fluciclovine PET-CT versus PSMA PET-CT for prostate cancer lesion detection after surgery and found that detection rates were significantly lower with 18f-Fluciclovine PET-CT than PSMA PET-CT.
What led you to this research?
Johannes Czernin, MD: 18F-fluciclovine (Axumin®, Blue Earth Diagnostics) was FDA approved and has been reimbursed by most insurance carriers including Medicare for some time. PSMA PET-CT was widely used in Europe and Asia for several years. However, prospective data to support the use of PSMA PET-CT imaging were lacking. Specifically, it was unknown whether PSMA PET-CT would perform better in patients with biochemical prostate cancer recurrence than 18F-fluciclovine. Based on published data from retrospective cohorts we thought that PSMA PET-CT should be superior for lesion detection especially in patients with low PSA levels. This is important because improved lesion detection could improve treatments of biochemical recurrence for instance by improved definition of radiation fields when subsequent radiation is considered. Thus, we thought that a direct comparison of the two tests in this population should be relevant.
Why is there a discrepancy in recommendations between EAU and NCCN guidelines in regard to recommending PSMA PET-CT versus 18F-fluciclovine PET-CT?
Dr. Czernin: PSMA PET-CT is an accepted diagnostic test in Europe, but it is not accepted in the US as it is not yet FDA approved. Therefore, it cannot be part of any recommendations.
What is the difference between 18F-fluciclovine PET-CT and PSMA PET-CT?
Dr. Czernin: 18F-fluciclovine measures the uptake of amino acids in prostate cancer cells. Amino acid consumption is increased in prostate cancer and other cancers.
PSMA PET-CT measures the expression Prostate Specific Membrane Antigen (PSMA) on prostate cancer cells. This enzyme is highly overexpressed in almost all prostate cancers.
Why is PSMA PET-CT more effective at detecting prostate cancer biochemical recurrence after radical prostatectomy than 18F-fluciclovine PET-CT?
Dr. Czernin: PSMA is highly expressed in prostate cancers but not much in normal tissues. This results in excellent image contrast. In other words, even small abnormalities can be seen because the signal is not hidden behind uptake in normal tissues. This is not entirely the case for 18F-fluciclovine where normal tissues such as muscles and bone marrow can also have relevant uptake which reduces image contrast. The one advantage of 18F-fluciclovine is that it is not excreted in the urinary bladder while PSMA is. This can sometimes result in difficulties assessing the prostate bed.
What advice would you give to community oncologists on which method to use: 18F-fluciclovine PET-CT versus PSMA PET-CT for patients with prostate cancer biochemical recurrence localization after radical prostatectomy?
Dr. Czernin: After FDA approval and when reimbursement is granted by Medicare, PSMA PET-CT will become the standard of care. Until then, 18F-fluciclovine should be used.
About Dr. Czernin
Johannes Czernin, MD currently serves as the Chief of the Ahmanson Translational Imaging Division at University of California Los Angeles. He has also served as the President of the Academy of Molecular Imaging and has published more than 200 peer-reviewed research papers.
For More Information
Calais J, Ceci F, Eiber M, et al (2019). 18F-fluciclovine PET-CT and 68Ga-PSMA-11 PET-CT in patients with early biochemical recurrence after prostatectomy: a prospective, single-center, single-arm, comparative imaging trial. Lancet Oncol. [Epub ahead of print] DOI10.1016/S1470-2045(19)30415-2
Transcript edited for clarity. Any views expressed above are the speaker's own and do not necessarily represent the views of i3 Health.