Objectives: This retrospective study aimed to evaluate the role of 68Ga-PSMA-I&T PET/CT in the primary staging of newly diagnosed prostate cancer (PCa), with a focus on the detection of metastatic nodal disease. Correlation of the rate of detection of metastatic disease by 68Ga-PSMA-I&T PET/CT with the Gleason score (GS) and serum prostate-specific antigen (PSA) was performed to determine the GS and PSA criteria defining patients who would benefit from 68Ga-PSMA-I&T PET/CT imaging for staging, risk stratification and therapy optimization.
Patients and methods: Patient data and images from 70 patients with a recent diagnosis of prostate cancer who had undergone 68Ga-PSMA-I&T PET/CT were analysed retrospectively. Data and images were analysed for the rate of detection of primary and metastatic PCa, and correlation with PSA and GS.
Results: The rate of detection of primary tumour by 68Ga-PSMA-I&T for patients with serum PSA less than 5 ng/ml was 73%. The corresponding rate was 90% for patients with PSA 5–10 ng/ml and 97% for patients with PSA more than 10 ng/ml. Metastatic PCa and/or infiltrative disease was detected in 24/70 study patients in total: 1/11 patients with PSA less than 5 ng/ml and 23/59 patients with serum PSA at least 5 ng/ml. The rate of detection of metastatic PCa was greater in patients with GS 9 or more (48%) relative to those with GS 8 (32%) or GS ≤7 (18%).
Conclusion: A role for 68Ga-PSMA-I&T PET/CT in primary PCa staging of high-grade disease (GS 8 or more and PSA >10 ng/ml) has been shown. There was a low rate of detection of PSMA-avid metastases in low-grade disease (GS 7 or less and PSA <5 ng/ml), suggesting that there is a limited role for this modality in such cases.
aTheranostics Australia, Richmond Quarter, East Fremantle
bDepartment of Medicine, Fiona Stanley Hospital, Murdoch
cTeleMed Health Services, Busselton
dDepartment of Medicine, Faculty of Health and Medical Sciences, University of Western Australia, Crawley
eOceanic Molecular, Perth Radiological Clinic, Nedlands, Western Australia
Correspondence to Danielle P. Meyrick, PhD, Theranostics Australia, Unit 106, 1 Silas St, East Fremantle 6158, Western Australia Tel: +61 890 911 081; fax: +61 893 877 866; e-mail: email@example.com
Received March 28, 2017
Received in revised form June 3, 2017
Accepted August 9, 2017