⁶⁸ Ga-PSMA PET/CT staging of newly diagnosed intermediate- and high-risk prostate cancer

Background: ⁶⁸ Ga-prostate-specific membrane antigen positron emission tomography/computerized tomography ( ⁶⁸ Ga-PSMA PET/CT) is part of the initial workup of patients with intermediate and high-risk prostate cancer provided by the Israeli national health services. Objectives: To assess the incidence of metastatic spread in consecutive patients with newly diagnosed cancer, and the potential added value of ⁶⁸ Ga-PSMA PET/CT to the staging imaging algorithm. Methods: Patients with newly diagnosed intermediate- and high-risk prostate cancer were referred for initial staging by ⁶⁸ Ga- PSMA PET/CT between May 2016 and April 2017. Blood prostatespecific antigen (PSA) levels, clinical history, imaging reports and histopathological reports (including Gleason scores) were obtained. Maximal standardized uptake values (SUVmax) were determined for the primary lesions detected within the prostate. Results: The study included 137 consecutive patients with intermediate- and high-risk disease who underwent ⁶⁸ Ga- PSMA PET/CT staging. Of these, 75 had ⁶⁸ Ga-PSMA uptake in both prostate lobes, 57 had unilateral uptake, and 5 patients had no uptake. SUVmax in the primary tumor correlated significantly with PSA levels. Thirty-five patients had increased uptake compatible with metastatic disease involving lymph nodes, bone, and viscera. Twenty-seven patients had available bone scintigraphy results: 18 (69%) of their 26 bone metastases detected by ⁶⁸ Ga-PSMA PET/CT were missed on bone scintigraphy. Conclusions: ⁶⁸ Ga-PSMA PET/CT shows promise as a sole wholebody imaging modality for assessing the presence of soft tissue and bone metastases in the setting of prostate cancer.