PET imaging in prostate cancer, future trends: PSMA ligands

Accurate staging is of utmost importance in patients with primary or recurrent prostate cancer. Current imaging techniques are unsuited for whole-body staging or limited by low sensitivity for small metastatic lesions. Prostate specific membrane antigen (PSMA) is over-expressed on prostate cancer cells. Thus, 68Ga-labelled small molecule PSMA ligands were developed to potentially overcome these limitations. A systematic search strategy was applied to review evidence for PSMA-directed imaging of prostate cancer. 175 publications were retrieved from The National Center for Biotechnology Information PubMed online database using the following search term: psma AND pet AND prostate cancer.

Sixteen publications were included based on the following criteria: original research; cohort study; reported diagnostic accuracy at primary diagnosis or biochemical recurrence; high quality of data acquisition and analysis. 68Ga-PSMA PET/CT stages lymph node involvement with a higher accuracy than CT and 68Ga-PSMA PET/MRI more accurately localizes primary prostate cancer than MRI or PET alone. Especially in patients with serum PSA <1 ng/mL sites of biochemical recurrence were detected better with 68Ga-PSMA PET/CT than with any other imaging modality. In summary, PSMA imaging demonstrates high accuracy for prostate cancer staging at primary diagnosis and biochemical recurrence. Future trials need to determine whether this superior diagnostic performance translates into improved clinical outcomes.