The present study is based on a retrospective analysis of Gallium-68 (68Ga)-labelled prostate-specific membrane antigen (68Ga-PSMA I&T) PET/CT performed in newly diagnosed, treatment-naïve prostate cancer (PCa) patients prior to definitive treatment.

A total of 82 men were included in the study and were imaged with 68Ga-PSMA I&T PET/CT to assess the distribution of PSMA-avid disease for staging purposes (11 with low-risk, 32 with intermediate-risk, and 39 with high-risk PCa). Forty patients (20 with intermediate- and 20 with high-risk disease) underwent subsequent radical prostatectomy with extended pelvic lymph node dissection which allowed for correlation of imaging findings with histopathologic data.

PSMA-positive disease was detected in 83% of patients with 66/82 (80.5%) primary tumours being visualized. PSMA-avid lymph nodes were recorded in 17/82 patients (20.7%, 3 with intermediate-risk and 14 with high-risk PCa); distant disease was found in 14/82 subjects (17.1%, 2 with intermediate-risk and 12 with high-risk PCa). No extraprostatic disease was found in low-risk PCa. SUVmax of primary tumours showed a weak but significant correlation with serum PSA values (r = 0.51, p < 0.001) and Gleason scores (GSC; r = 0.35, p = 0.001), respectively. In correlation with histopathology, calculated per-region sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for detection of lymph node metastases were 35.0%, 98.4%, 63.6%, 95.0%, and 93.0%, respectively.

In patients with initial diagnosis of intermediate- and high-risk prostate cancer, 68Ga-PSMA I&T PET/CT emerges as a relevant staging procedure by identifying nodal and/or distant metastases. Due to the low prevalence of extraprostatic disease, its value seems to be limited in low-risk disease.

European journal of nuclear medicine and molecular imaging. 2019 Sep 16 [Epub ahead of print]

Wojciech Cytawa, Anna Katharina Seitz, Stefan Kircher, Kazuhito Fukushima, Johannes Tran-Gia, Andreas Schirbel, Tomasz Bandurski, Piotr Lass, Markus Krebs, Wojciech Połom, Marcin Matuszewski, Hans-Jürgen Wester, Andreas K Buck, Hubert Kübler, Constantin Lapa

Department of Nuclear Medicine, Medical University of Gdańsk, Smoluchowskiego Str. 17, 80-952, Gdańsk, Poland., Department of Urology, University Hospital Würzburg, Würzburg, Germany., Institute of Pathology, Comprehensive Cancer Center Mainfranken (CCCMF), University of Würzburg, Würzburg, Germany., Department of Nuclear Medicine, University Hospital Würzburg, Oberdürrbacher Str. 6, 97080, Würzburg, Germany., Department of Radiology Informatics and Statistics, Medical University of Gdańsk, Gdańsk, Poland., Department of Urology, Medical University of Gdansk, Gdańsk, Poland., Pharmaceutical Radiochemistry, Technische Universität München, Munich, Germany., Department of Nuclear Medicine, University Hospital Würzburg, Oberdürrbacher Str. 6, 97080, Würzburg, Germany. .