The role of 68Ga-PSMA-I&T PET/CT in the pretreatment staging of primary prostate cancer

Nucl Med Commun. 2017 Nov;38(11):956-963. doi: 10.1097/MNM.0000000000000738.

Abstract

Objectives: This retrospective study aimed to evaluate the role of Ga-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 Ga-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 Ga-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 Ga-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 Ga-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 Ga-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.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Edetic Acid / analogs & derivatives*
  • Humans
  • Image Processing, Computer-Assisted
  • Male
  • Middle Aged
  • Neoplasm Staging
  • Oligopeptides*
  • Positron Emission Tomography Computed Tomography*
  • Prostate-Specific Antigen / blood
  • Prostatic Neoplasms / blood
  • Prostatic Neoplasms / diagnostic imaging*
  • Prostatic Neoplasms / pathology*
  • Prostatic Neoplasms / therapy
  • Retrospective Studies

Substances

  • Oligopeptides
  • gallium 68 PSMA-11
  • Edetic Acid
  • Prostate-Specific Antigen