Performance of Ga-68 PSMA PET/CT for diagnosis and grading of local prostate cancer

Timothy N Kwan; Sandra Spremo; Amy Y M Teh; David McHarg; Isaac Thangasamy; Henry H Woo

doi:10.1016/j.prnil.2020.07.008

Performance of Ga-68 PSMA PET/CT for diagnosis and grading of local prostate cancer

Prostate Int. 2021 Jun;9(2):107-112. doi: 10.1016/j.prnil.2020.07.008. Epub 2020 Aug 10.

Authors

Timothy N Kwan¹, Sandra Spremo¹, Amy Y M Teh¹, David McHarg², Isaac Thangasamy³, Henry H Woo¹

Affiliations

¹ University of Sydney, Australia.
² Northern Nuclear Medicine, Australia.
³ Faculty of Medicine, University of Queensland, Brisbane, Queensland, Australia.

Abstract

Background: We aimed to evaluate the utility of prostate-specific membrane antigen (PSMA) PET/CT for the detection of local disease within the prostate.

Methods: This is a retrospective review of a single-center experience evaluating intraprostatic detection rates compared with final histopathology in a radical prostatectomy (RP) population. Seventy-two patients had PSMA PET/CT scan performed as part of their primary staging. Intraprostatic PSMA PET/CT avidity was assessed. PSMA PET/CT uptake was retrospectively correlated with patient characteristics including final histopathology, MRI Prostate Imaging Reporting and Data System (PI-RADS) score, clinical tumor stage, prostate-specific antigen (PSA) level, and patient age.

Results: The sensitivity of PSMA PET/CT for the detection of RP-confirmed prostate cancer was 81.2%. Much higher sensitivity was found within certain subpopulations. The patient characteristics that most strongly correlated with focal intraprostatic PSMA PET/CT uptake were patient age (Kendall's tau coefficient τ_b = 0.24, p < 0.05) and clinical T stage (τ_b = 0.21, p < 0.05).The International Society of Urological Pathology (ISUP) grade group from final RP was predicted by standardized uptake value (SUV_max) and to a lesser extent PSA and the maximal dimension of PET-avid lesions. SUV_max monotonically increased with ISUP grade group. If SUV_max was above 10 g/mL, the final RP histopathology had a relative risk of 2.3 (95% CI 1.3-4.1) of being ISUP grade group 5.

Conclusion: This trial provides early evidence that PSMA PET/CT assists in the grading of prostate cancer and suggests that the imaging modality is particularly accurate in subpopulations including the elderly and those with palpable disease.

Keywords: Observational study; Positron-emission tomography; Prostatic neoplasms.