Promise of PET Imaging in Prostate Cancer, Improvement or Waste of Money? With Great Power Comes Great Responsibility - Beyond the Abstract

Over the last few years, we have witnessed, as medical professionals with a specific interest for prostate cancer research, a major shift of paradigm to the way we approach prostate cancer imaging. This came in the form of a very small molecule.

PSMA (prostate specific membrane antigen) based imaging has quickly become the hottest topic in the field of nuclear medicine and shortly after an appealing tool for urologists worldwide.

First studies from 2015 conducted in Germany1 where the first tracer was synthesized and in Australia2 highlighted the superior sensitivity and detection rate of Ga68-PSMA PET tracers over choline based tracers at biochemical recurrence. More importantly, PSMA PET/CT has provided excellent detection rates even at low PSA values where other molecular imaging modalities struggle.3

Since then, a plethora of studies have consistently confirmed these preliminary findings, and PSMA PET/CT is now the preferred imaging modality for urologist at BCR in the countries where it is available. Moreover, recent publications and preliminary results from well-designed prospective studies (namely PRO-PSMA study, ACTRN12617000005358)4 are suggesting that PSMA PET/CT might be a useful imaging modality even in the staging setting.

This important data seems to confirm the absolutely fundamental role of PSMA based imaging for prostate cancer management, suggesting more structured incorporation of molecular imaging modalities such as PSMA PET/CT in current guidelines might be timely.

The role of molecular imaging specialists and clinicians should be to properly use PSMA PET/CT when appropriate and truly relevant for the management of patients while avoiding un-necessary scans in patients that have very low probability of any metastatic disease (such as low and intermediate risk with favorable characteristics)  or have been adequately managed with other modalities.

This is even more important when considering the role of PSMA based imaging in a theranostic setting where the same molecule can then be targeted for radio-ligand therapy (RLT) with Lutetium based PSMA.

Only with responsible use of PSMA PET/CT scans, we can guarantee that, in the future which we hope is near, regulatory bodies worldwide will officially acknowledge the indispensable role of this imaging modality for the management of prostate cancer.

Written by: Joshua James Morigi, FRACP, PET/CT Unit Head Physician, Royal Darwin Hospital, Darwin, Australia & Stefano Fanti, MD, Director of Nuclear Medicine Division of the PET Unit, Policlinico S. Orsola, Director, Speciality School of Nuclear Medicine, University of Bologna, Bologna, Italy.

References:

  1. Afshar-Oromieh A, Avtzi E, Giesel FL, Holland-Letz T, Linhart HG, Eder M, et al. The diagnostic value of PET/CT imaging with the 68Ga-labelled PSMA ligand HBED-CC in the diagnosis of recurrent prostate cancer. Eur J Nucl Med Mol Imaging. Springer Science + Business Media; 2014;42:197–209
  2. Morigi JJ, Stricker PD, Van Leeuwen PJ, Tang R, Ho B, Nguyen Q, et al. Prospective Comparison of 18F-Fluoromethylcholine Versus 68Ga-PSMA PET/CT in prostate cancer patients who have rising PSA after curative treatment and are being considered for targeted therapy. J Nucl Med. 2015;56:1185–90.
  3. Graziani T, Ceci F, Castellucci P, Polverari G, Lima GM, Lodi F, et al. (11)C-Choline PET/CT for restaging prostate cancer. Results from 4,426 scans in a single-centre patient series. Eur J Nucl Med Mol Imaging. 2016.
  4. Hofman MS, Murphy DG, Williams SG, Nzenza T, Herschtal A, De Abreu Lourenco R, et al. A prospective randomized multicentre study of the impact of gallium-68 prostate-specific membrane antigen (PSMA) PET/CT imaging for staging high-risk prostate cancer prior to curative-intent surgery or radiotherapy (proPSMA study): clinical trial protocol. BJU Int. 2018;122:783–93.
  5. Joshua James Morigi, Jack Anderson, Stefano Fanti, Promise of PET imaging in prostate cancer improvement or waste of money? Current Opinion in Urology: October 2019. doi: 10.1097/MOU.0000000000000684.
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