Although prostate cancer is the second most common cancer in men, clinicians and patients have had to rely on statistical models for treatment, as effective imaging was not available until recently.
In the past decade, multiparametric MRI enabled accurate detection of tumors within the prostate. Unfortunately, CT and bone scans are not sensitive to early extraprostatic disease, which typically presents with small tumors below the detection threshold of these modalities. Prostate cancer also has low glycolytic rates and poor avidity on 18F-FDG PET/CT. However, as reviewed in a recent article (Boustani AM, Pucar D, Saperstein L. Molecular Imaging of Prostate Cancer. Br J Radiol. 2018), new metabolic and receptor-targeting molecular agents are capable of detecting small nodal and osseous tumors. Two metabolic PET agents, 18F-Fluciclovine (Axumin) and 11C-Choline were recently FDA approved and incorporated in NCCN guidelines for early detection of prostate cancer post-treatment relapse. Axumin PET/CT is routinely used at Yale.
New agents targeting prostate-specific membrane antigen (PSMA) may surpass Axumin in early detection of extraprostatic disease. The Department of Radiology & Biomedical Imaging at Yale School of Medicine participated in two existing international trials with PSMA agents in patients with biochemical relapse of prostate cancer. Lawrence Saperstein, MD, chief of nuclear medicine, served as Yale’s principal investigator for both trials.
CONDOR is a phase 3, multi-center, open-label study to assess the diagnostic performance and clinical impact of 18F-DCFPyL PET/CT imaging results in men with suspected recurrence of prostate cancer. PROfind is a phase 1/2 open-label, multi-center, safety and tolerability study of a single dose of 68Ga-PSMA-R2 in patients with biochemical relapse (BR) and metastatic prostate cancer (mPCa). Saperstein, Darko Pucar, MD, Research Coordinator Svetlana Vassilieva, MD, MS, Eliot Funai, CCRP, and their clinical colleagues conducted the CONDOR and PROfind trials, which surpassed their expectations. CONDOR trial enrolled 58 patients and enrolled 27 patients (planned 20). The PROFind trial enrolled six patients (planned four). Although the results of the trials are pending, subcentimeter tumors were detected with 18F-DCFPyL in structurally normal nodes and bones on CT.
"We can now envision how the use of these new molecular agents can be expanded to radiation treatment, planning and monitoring response to systemic therapy,” Saperstein said.
A PET/MRI hybrid scanner may provide one-stop imaging of local and regional nodal and metastatic prostate cancer. “The future of prostate cancer imaging is bright and Yale has a major role to play in its clinical translation for the benefit of our patients,” Pucar said.