MP09-15\u200368GA-PSMA-11 PET/CT IN RECURRENT PROSTATE CANCER: EFFICACY IN DIFFERENT CLINICAL STAGES OF PSA FAILURE

Abstract

INTRODUCTION AND OBJECTIVES: The primary objective was the evaluation of Gallium 68(68Ga)-prostate-specific membrane antigen (PSMA)-11 positron emission tomography/computed tomography (PET/CT) detection rate for prostate cancer (PCa) relapse site identification, stratifying the population for different clinical stages of biochemical recurrence (BCR). Secondary aims were:1)to evaluate the association of clinical/pathologic features and 68Ga-PSMA-11 PET/CT detection rate, 2)to compare 68Ga-PSMA-11 PET/CT with other imaging procedures, and 3)to evaluate the positive predictive value (PPV) in a per-patient analysis. METHODS: This population was enrolled through a prospective, open label, single-center trial performed at the Nuclear Medicine of the University Hospital of Bologna (Eudract: 2015-004589-27 OsSC). Inclusion criteria were: (1) proven PCa, (2) surgery or radiotherapy as definitive therapy, (3) proven BCR, (4) prostate specific antigen (PSA)0.2–2 ng/ml, (5) age≥35 years, and (6) willing to sign an informed consent. Different patterns of BCR were identified by referent physicians as follows: (a) persisting detectable PSA after radical prostatectomy in 13.5% (45/332) of patients (subgroup 1), (b) first-time PSA failure after radical therapy in 44.9% (149/332; subgroup 2), and (c) PSA increase after salvage or hormonal therapy in 41.6% (138/332; subgroup 3). RESULTS: Primary objective: 68Ga-PSMA-11 PET/CT detection rate was 53.6% (CI 95% 48.1%–59.1%). In a patient-based analysis, disease confined to pelvis (prostate bed and/or lymph-nodes) was detected in 24.7% of cases (82/332). The presence of at least one distant lesion was observed in 28.9% of cases (96/332). The detection rates were: subgroup 1=64.5%, subgroup 2=45.6%, and subgroup 3=58.7%. Secondary objectives: 1)PSA (p=0.041) and PSAdt (p=0.001) showed association with 68Ga-PSMA-11 PET/CT detection rate, and 2) correlative imaging was available in 73.2% of patients (243/332). When 68Ga-PSMA-11 PET/CT was positive, correlative imaging resulted negative in 83% of cases (108/130). 3) The PPV was 96.2%. CONCLUSIONS: 68Ga-PSMA-11 PET/CT is efficient in detecting local vs systemic disease in PCa patients presenting PSA failure after radical therapy. Furthermore, 68Ga-PSMA-11 PET/CT detection rate is different depending on the clinical stage of BCR. Figure. No caption available. Table. No title available. Table. No title available. Source of Funding: none