EO8 Initial experience with PSMA-radioguided surgery in prostate cancer patients

Abstract

Introduction & Objectives: Staging of primary intermediate and high-risk prostate cancer patients before curative treatment usually comprises bone scintigraphy and CT orMRI of the abdomen. Recently, Glu-NH-CO-NH-Lys-(Ahx)-[(68)Ga(HBED-CC)] as a novel 68Galliumlabelled ligand of the prostate-specific membrane antigen (68GaHBED-PSMA) has been developed. First reports state high sensitivity and specificity in the detection of prostate cancer lesions. Thus, the aim of this prospective analysis was to investigate 68Ga-HBED-PSMA PET/MR for staging in this patient cohort and correlate it with the results of postoperative histological findings. Material & Methods: This analysis included 53 patients prior to planned radical prostatectomy with intermediate or high-risk prostate cancer according to d’Amico classification. After injection of 100–150 MBq 68Ga-HBED-PSMA a fully-diagnostic PET/MR including multiparametric prostate MRI was performed and images were reviewed by one nuclear medicine physician and one radiologist in consensus. Visualization of local tumor, evidence of lymph node or distantmetastaseswas evaluated and compared to postoperative histological findings. Results: Despite unremarkable conventional imaging 68Ga-HBEDPSMA PET/MRI revealed metastasized disease in two patients who therefore did not undergo radical prostatectomy. Tumor involvement of the prostate could be visualized by 68Ga-HBED-PSMA PET in 88.3% of patients (45/51). In patients with PSMA-positive primary tumor 68Ga-HBED-PSMA PET detected 11 out of 13 patients with histological lymph node involvement (sensitivity: 84.6%) and correctly classified 31 out of 32 patients without histological evidence of lymph node metastases (specificity: 96.6%; accuracy 93.3%). Of note, the two patients with lymph node metastases that were missed by 68GaHBED-PSMA PET only showed micrometastasis in one lymph node. Conclusions: In this initial series, 68Ga-HBED-PSMA PET/MRI showed a high detection rate of the primary tumor within the prostate and proved to be of high sensitivity, specificity and accuracy regarding lymph node staging. Therefore, 68Ga-HBED-PSMA PET/MRI as single investigation might have the potential to stage intermediate and high-risk prostate cancer patients more accurately than standard imaging.