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292 Background: Prostate-specific membrane antigen ligand positron emission tomography (PSMA PET) induced management changes in up to every second patient in smaller clinical trials. We aim to determine the impact of 68Ga-PSMA-11 PET/CT on management of biochemically recurrent prostate cancer in a large prospective cohort. Methods: We report management changes following PSMA PET, a secondary endpoint of a prospective multicenter trial in men with prostate cancer biochemical recurrence (NCT02940262 and NCT03353740). Pre-PET, Post-PET and Post-Treatment Questionnaires were sent to referring physicians recording working clinical summaries, intended and implemented therapeutic and diagnostic management. Results: Intended management change occurred in 260/382 (68%) patients. Intended change was considered major in 176/382 (46%) patients. Management pathway aligned with PET findings, i.e. change towards local/focal therapy for locoregional disease (54/126 patients, 44%) and towards systemic therapy or combination approaches for metastatic disease (106/153 patients, 69%). Intended management was implemented in 160/206 (78%) patients. Perceived site of disease was unknown in 259/382 (68%) patients before and 111/382 (29%) patients after PSMA PET. A total of 150 intended diagnostic tests, mostly CT (n=43, 29%) and bone Scans/NaF-PET (n=52, 35%), were prevented by PSMA PET. A total of 73 tests, mostly biopsies (n=44, 60%) requested by the study protocol, were triggered. Conclusions: Disease localization by PSMA PET translated into management changes in more than half of patients with biochemical recurrence of prostate cancer. More than twice as many diagnostic tests were prevented than triggered following PET. Clinical trial information: NCT02940262 and NCT03353740.

5014 Background: This is a prospective single-center, single-arm, head-to-head phase 3 study of paired 18F-fluciclovine (FACBC) and 68Ga-PSMA-11 (PSMA) PET/CT scans for localizing early biochemical recurrence (BCR) of prostate cancer (PCa) after radical prostatectomy (RP) (NCT02940262). Methods: Fifty consecutive patients with BCR and prostate specific antigen (PSA) levels ranging from ≥0.2 to ≤2.0 ng/mL without any prior salvage therapy were included. All patients underwent FACBC and PSMA PET/CT scans within ≤15 days. PET/CT scans were each interpreted by 3 independent blinded expert readers not involved in study design and data acquisition. Region consensus interpretation (T,N,M1a,M1b,M1c) was generated based on majority rule in cases of reader disagreement (2 vs 1). PET/CT scans were considered as positive if any region was rated as positive. Detection rates per-patient and per-region served as primary study endpoint. Results: Median time interval between the 2 scans was 6 days (range 1-15). Median PSA level at the time of imaging was 0.50 ng/ml (mean 0.63; range 0.2-2.0 ng/ml). The detection rates were significantly lower with FACBC than with PSMA PET/CT per-patient (26% vs 56%; p = 0.003) and per-region for pelvic nodes (N) (8% vs 30%; p = 0.003) or any extra-pelvic lesions (M) (0% vs 16%; p = 0.008). Reader agreement for PSMA PET/CT image interpretations was significantly higher than for FACBC PET/CT (0.67 vs 0.20; p = 0.015). Conclusions: In patients with BCR and low serum PSA levels after RP, PSMA PET/CT demonstrates higher detection rates and superior reader agreement when compared with FACBC PET/CT. Therefore, PSMA PET/CT should be the imaging modality of choice in patients with early BCR. Clinical trial information: NCT03515577.

5001Background: 68Ga-PSMA11 PET/CT provides improved localization of biochemically recurrent prostate cancer. For approval and reimbursement, accuracy needs to be established in a prospective study...