MP36-19 What is the accuracy of 68 GA-PSMA PET/CT in detecting primary prostate cancers compared to multiparametric MRI?

Abstract

PSMA PET/CT has demonstrated superior sensitivity in detecting prostate cancer metastases compared to traditional staging modalities and seen a high degree of utilisation in the Australian setting. However, there is little data published on the role of PSMA PET/CT in detecting and diagnosing primary prostate cancer. We compared the accuracy of PSMA PET/CT to multiparametric MRI for the detection of clinically significant primary prostate cancer. A local prospective database (REDCap-Monash) was maintained on patients who underwent MRI in our group urology practice from July 2013 to December 2017. All patients who had an MRI for diagnosis of prostate cancer, subsequent transperineal biopsy, and a PSMA PET/CT for initial staging were included, with significant cancer being defined as greater than or equal to Gleason 3+4=7 (ISUP Grade Group 2). The database contained 2,283 patients who underwent prostate MRI. 239 patients subsequently underwent both biopsy and PSMA PET/CT. 202 biopsies (84.5%) showed significant cancer. Of the non-significant cancer cases, 21 (8.8%) revealed Grade Group 1 lesions and 16 (6.7%) were benign. For significant cancers, 189 PSMA PET/CT scans demonstrated local PSMA avidity in the prostate, compared to 174 positive (PIRADS 4 or 5) MRI scans.