(UroToday.com) The 2023 European Association of Urology (EAU) annual congress held in Milan, Italy between March 10th and 13th, 2023 was host to an EAU Section of Oncologic Urology (ESOU) session addressing progress and controversies in urologic oncology. In this case-based debate moderated by Dr. Michael Baboudjian, Professor Hashim Ahmed was tasked with arguing against PSMA-PET/CT supplanting multiparametric MRI (mpMRI) as a tool for prostate cancer detection.
Professor Ahmed began by asking the question: What is the clinical need in the current prostate cancer diagnosis paradigm? How does PSMA-PET/CT fit in? Is it as a replacement, tirage, or add-on tool?
The Rapid Assessment for Prostate Imaging and Diagnosis (RAPID) diagnostic pathway was introduced to potentially reduce patient and healthcare burdens and standardize delivery of pre-biopsy multiparametric magnetic resonance imaging (MRI) and transperineal biopsy. A total of 2130 patients from three centers completed the RAPID pathway, whereby patients with an MRI score of 4 or 5 and those with PSA density ≥0.12 and an MRI score 3 were advised to undergo a biopsy. Using this approach, a biopsy could be omitted in 43% of patients (920/2130). As such, the MRI, when combined with PSA density, acts as a valuable “triage” tool.1
But what about cancer that is not picked up on MRI (~15-25%)? Post-hoc analyses of PROMIS and PICTURE suggest that the undetected tumor is small volume (3-4 mm).
Professor Ahmed then asked: “Is PSMA imaging really that great?”. His concern with the PRIMARY score, derived from the PRIMARY trial combining MRI and PSMA-PET/CT in the primary diagnostic setting, is that even patients with a PRIMARY 1-2 score (i.e. a lower risk of csPCa), the percentage of missed GG2 or worse disease is significant (~10% and 30% for PRIMARY score 1 and 2, respectively).4
Furthermore, mpMRI offers fine detail imaging, as compared to PSMA PET/CT, which can appear as a ‘blob within a blob’.
What about cost? One must keep in mind that cost varies country by country with PSMA-PET/CT costs significantly lower in countries such as Australia. In Europe, Professor Ahmed noted that the average cost for a PET-PSMA/CT was 1,500 Euros, compared to 250 Euros for an MRI. Furthermore, economic simulation studies suggest the following costs if MRI and PSMA are combined together:
- mpMRI alone: 125 to 250 million Euros
- PSMA as replacement: 750 to 1,500 million Euros
- PSMA for 40% MRI negative cases: 300 to 600 million Euros
- PSMA as additional test in all: 850 to 875 million Euros
Importantly, the radiation exposure is not insignificant in patients receiving a PSMA-PET/CT, with a radiation dose of 8.4 mSv:
Professor Ahmed concluded as follows:
- PSMA PET imaging for primary diagnosis of PCa in men at risk is a “plaything of the Australian…Finding an abundance of a new test flooding into their market. They are looking for a problem that does not exist.”
- Majority of patients in the real world cannot access PSMA imaging for staging, due to uncertainty over clinical utility and lack of facilities, let alone primary diagnosis.
- PSMA is costly, has a significant radiation dose, and shows you a ‘blob within blobs’ to target.
- We have enough problems with access and quality control of pre-biopsy MRI
Presented by: Professor Hashim U. Ahmed, BM BCh (Oxon), Professor and Chair of Urology, Imperial College London, London, UK
Written by: Rashid K. Sayyid, MD, MSc – Society of Urologic Oncology (SUO) Clinical Fellow at The University of Toronto, @rksayyid on Twitter during the 2023 European Association of Urology (EAU) Annual Meeting, Milan, IT, Fri, Mar 10 – Mon, Mar 13, 2023.
References:
1. Eldred-Evans, et al. The rapid assessment for prostate imaging and diagnosis (RAPID) prostate cancer diagnostic pathway. BJU Int. 2022: online ahead of print
2. Ahmed, et al. Diagnostic accuracy of multi-parametric MRI and TRUS biopsy in prostate cancer (PROMIS): a paired validating confirmatory study. Lancet, 2017;389(10071):815-822
3. Simmons, et al. Br J Cancer, 2017.
4. Emmett, et al. The PRIMARY Score: Using Intraprostatic 68Ga-PSMA PET/CT Patterns to Optimize Prostate Cancer Diagnosis. J Nucl Med;2022:63(11):1644-1650.
Read the PRO Debate: EAU 2023: Case-Based Debate: Will PSMA PET Supplant Multiparametric MRI for Prostate Cancer Detection? Case Presentation – Pro