ASCO 2021: PSMA-PET/CT Registry for Recurrent Prostate Cancer (PREP): Initial Findings from a Single Center

(UroToday.com) Advances in imaging have dramatically reshaped prostate cancer diagnosis, staging, and treatment. While multiparametric MRI (mpMRI) of the prostate has dramatically changed prostate cancer diagnosis, molecularly-targeted imaging has reshaped disease staging and detection of recurrent disease. Conventional imaging approaches using including computed tomography (CT) and bone scan have relatively limited sensitivity to detect disease recurrence following initial local therapy. The proPSMA trials, and other studies, have demonstrated that prostate-specific membrane antigen (PSMA) targeting PET radiopharmaceuticals detect disease not identified based on conventional imaging, with greater accuracy. In the Prostate, Testicular, Penile Poster session at the 2021 American Society of Clinical Oncology 2021 Annual Meeting, Dr. Michael Uy presented results of a multi-center registry assessing the ability of PSMA targeted PET/CT to detect sites of disease recurrence and affect patient management.


To do so, the authors performed a multi-center prospective registry study among six Ontario centers. Re-staging PSMA-PET/CT was performed in seven different clinical scenarios (NCT03718260): following radical prostatectomy with node-positive disease or a persistently detectable PSA; with biochemical recurrence following radical prostatectomy; biochemical recurrence following radical prostatectomy and post-operative radiotherapy; biochemical recurrence following local therapy (radical prostatectomy or radiotherapy) while on androgen deprivation therapy; biochemical recurrence following radical prostatectomy following metastasis-directed therapy; biochemical recurrence following primary radiotherapy; and a separate PET access cohort with independent adjudication for eligibility.

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To be eligible, patients’ treating physicians must attest whether PSMA-PET/CT results would change the planned management strategy.

In this presentation, Dr. Uy provided initial results from a since center. At this center, 253 patients were included and underwent PSMA-PET/CT. At baseline, the median patient age was 71 years (range 50-102 years) and median PSA was 2.7 ng/mL (range 0.04-134.0 ng/mL). Most included patients (n=59; 23.3%) had evidence of biochemical recurrence following radical prostatectomy (cohort 2). In patients with negative conventional imaging (CT and bone scan), PSMA-PET/CT detected disease sites in 68.5% of patients (170/248), which resulted in changes in treatment approach for 67.8% of patients (137/202). Management changes occurred in 72.1% of patients who had previously received radiotherapy and 64.3% of patients who had previously received radical prostatectomy.

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The authors conclude that the use of PSMA-PET/CT detected evidence of disease that was not apparent on conventional imaging, resulting in management changes in the majority of patients.

Presented by: Michael Uy, MD, McMaster University Hamilton, Hamilton, ON, Canada

Written by: Christopher J.D. Wallis, Urologic Oncology Fellow, Vanderbilt University Medical Center Contact: @WallisCJD on Twitter at the 2021 American Society of Clinical Oncology (ASCO) Annual Meeting, Virtual Annual Meeting #ASCO21, June, 4-8, 2021
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