Abstract
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Objectives: To investigate the lesion detection rate of 18F-DCFPyL PET/CT, a PSMA targeted PET agent, in patients with biochemical relapse prostate cancer after primary local therapy.
Methods: This is a prospective IRB-approved study including 22 patients with documented biochemical recurrence (average PSA of 4.0 ng/mL, range 0.37-13.3 ng/mL) after local therapy, either radical prostatectomy (n= 13), post radiation therapy (n=5) or both (n=4), with negative standard conventional anatomical imaging. All patients underwent whole body 18F-DCFPyL-PET/CT (299.5±10.8 MBq) at 2 h p.i, and multiparametric MRI (mpMRI), 2 weeks apart. Lesion detection rate of 18F-DCFPyL-PET was assessed and correlated with mpMRI findings, and pre-scan PSA levels.
Results: Nineteen patients (86.3%) showed at least one positive DCFPyL-avid lesion, identifying a total of 53 lesions: 9 in the prostate bed, 36 lymph nodes, and 8 distant sites. The detection rates were 80% (n=4/5), 50% (n=1/2), 100% (n=4/4), and 90.9% (n=10/11) for PSA levels of >0.2 to <0.5, >0.5 to 1.0, >1 to 2.0, and ≥ 2.0 ng/mL, respectively. The 18F-DCFPyL-PET and mMRI findings were concordant for 11 lesions (20.7%), while 18F-DCFPyL exclusively detected additional 42 lesions (79.2%), 16 located outside the mMR field of view. Tumor recurrence was confirmed by either biopsy (5/19 pts), or matched mMRI (3/19); 2 patients had negative biopsy (an inflammatory lymph node and a rib fibrous dysplasia); 1 patient refused biopsy; 1 patient had a lesion not amenable for biopsy; and 7 patients are pending for biopsy and/or clinical decision. Patient accrual is ongoing for this trial and more results will be available at the time of presentation.
Conclusions: 18F-DCFPyL PET imaging is helpful in identifying lesion detection in 86.3% of patients with biochemical recurrence prostate cancer. Most importantly, it reveals a high number of positive findings in the clinically important range of low PSA values (<0.5 ng/mL), which may substantially impact the further clinical management.