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Diagnostic Accuracy of Prostate Specific Membrane Antigen 18F-DCFPyL PET/CT in Prostate Cancer Patients
TAKE-HOME MESSAGE
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In this multi-institutional prospective study, the performance characteristics of an emerging PET ligand, 18F-DCFPyL, was evaluated. In the high-risk prostate cancer patient group undergoing prostatectomy, the median positive predictive value of 18F-DCFPyL PET/CT imaging was 86.7%, the negative predictive value was 83.2%, and the specificity and sensitivity were 97.9% and 40.3%, respectively. In the patient group with suspicion for recurrence, the positive predictive value of the conventional imaging was 81.9% with a sensitivity of 95.8%.
- These data suggest that 18F-DCFPyL offers a superior imaging alternative to conventional imaging for the detection of pelvic nodal disease. While a negative scan does not guarantee disease absence, urologists should be aware of the importance of PSMA PET agents, as these agents will likely alter the way prostate cancer is staged and treated.
abstract
This abstract is available on the publisher's site.
Access this abstract nowPURPOSE
Prostate specific membrane antigen-targeted positron emission tomography/computerized tomography has the potential to improve the detection and localization of prostate cancer. OSPREY was a prospective trial designed to determine the diagnostic performance of 18F-DCFPyL-positron emission tomography/computerized tomography for detecting sites of metastatic prostate cancer.
MATERIALS AND METHODS
Two patient populations underwent 18F-DCFPyL-positron emission tomography/computerized tomography. Cohort A enrolled men with high-risk prostate cancer undergoing radical prostatectomy with pelvic lymphadenectomy. Cohort B enrolled patients with suspected recurrent/metastatic prostate cancer on conventional imaging. Three blinded central readers evaluated the 18F-DCFPyL-positron emission tomography/computerized tomography. Diagnostic performance of 18F-DCFPyL-positron emission tomography/computerized tomography was based on imaging results compared to histopathology. In cohort A, detection of pelvic nodal disease (with specificity and sensitivity as co-primary end points) and of extrapelvic metastases were evaluated. In cohort B, sensitivity and positive predictive value for prostate cancer within biopsied lesions were evaluated.
RESULTS
A total of 385 patients were enrolled. In cohort A (252 evaluable patients), 18F-DCFPyL-positron emission tomography/computerized tomography had median specificity of 97.9% (95% CI: 94.5%–99.4%) and median sensitivity of 40.3% (28.1%–52.5%, not meeting prespecified end point) among 3 readers for pelvic nodal involvement; median positive predictive value and negative predictive value were 86.7% (69.7%–95.3%) and 83.2% (78.2%–88.1%), respectively. In cohort B (93 evaluable patients, median prostate specific antigen 11.3 ng/ml), median sensitivity and positive predictive value for extraprostatic lesions were 95.8% (87.8%–99.0%) and 81.9% (73.7%–90.2%), respectively.
CONCLUSIONS
The primary end point for specificity was met while the primary end point for sensitivity was not. The high positive predictive value observed in both cohorts indicates that 18F-DCFPyL-positive lesions are likely to represent disease, supporting the potential utility of 18F-DCFPyL-positron emission tomography/computerized tomography to stage men with high-risk prostate cancer for nodal or distant metastases, and reliably detect sites of disease in men with suspected metastatic prostate cancer.
Additional Info
Disclosure statements are available on the authors' profiles:
A Phase 2/3 Prospective Multicenter Study of the Diagnostic Accuracy of Prostate Specific Membrane Antigen PET/CT With 18F-DCFPyL in Prostate Cancer Patients (OSPREY)
J Urol 2021 Jul 01;206(1)52-61, KJ Pienta, MA Gorin, SP Rowe, PR Carroll, F Pouliot, S Probst, L Saperstein, MA Preston, AS Alva, A Patnaik, JC Durack, N Stambler, T Lin, J Jensen, V Wong, BA Siegel, MJ MorrisFrom MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
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The use of PSMA PET scan imaging is now FDA-approved in the United State as a consequence of the decision on May 27, 2021 with regards to Pylarify.
It is clear that PSMA PET imaging provides greater sensitivity in terms of localizing disease, but proving the point is exceptionally difficult. If your scan is better than any other scan, how do you demonstrate that the best scan is detecting actual disease?
It is readily acknowledged by this reviewer that biopsy of metastatic legions is an imperfect art, and determining whether or not a PSMA-positive lesion actually represents cancer is an extremely difficult task.
Taken together, these incredibly difficult-to-perform studies, in my mind, take a secondary seat to the fact that PSMA imaging is, without a doubt, a better method to detect metastatic disease, both in patients initially diagnosed for those who are at risk of metastases and those who have PSA recurrence after initial definitive therapies.
I anticipate that PSMA PET will very rapidly become the method of choice for staging patients for prostate cancer, in both the recurrent setting and in those who have significant risks for metastatic disease when initially diagnosed. PSMA PET imaging is a better form of imaging, and, yet, we still have much to learn and can anticipate a series of more publications in the future providing clarity on the utility and outcomes associated with this important imaging technique.