The accuracy and intra- and interobserver variability of PSMA PET/CT for the local staging of primary prostate cancer

Maarten L Donswijk*, Rosemarijn H Ettema, Dennie Meijer, Maurits Wondergem, Zing Cheung, Elise M Bekers, Pim J van Leeuwen, Roderick C N van den Bergh, Henk G van der Poel, André N Vis, Daniela E Oprea-Lager

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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Abstract

PURPOSE: 

Prostate-specific membrane antigen (PSMA) positron emission tomography/ computed tomography (PET/CT) is recognized as the most accurate imaging modality for detection of metastatic high-risk prostate cancer (PCa). Its role in the local staging of disease is yet unclear. We assessed the intra- and interobserver variability, as well as the diagnostic accuracy of the PSMA PET/CT based molecular imaging local tumour stage (miT-stage) for the local tumour stage assessment in a large, multicentre cohort of patients with intermediate and high-risk primary PCa, with the radical prostatectomy specimen (pT-stage) serving as the reference standard.

METHODS:

 A total of 600 patients who underwent staging PSMA PET/CT before robot-assisted radical prostatectomy was studied. In 579 PSMA positive primary prostate tumours a comparison was made between miT-stage as assessed by four nuclear physicians and the pT-stage according to ISUP protocol. Sensitivity, specificity and diagnostic accuracy were determined. In a representative subset of 100 patients, the intra-and interobserver variability were assessed using Kappa-estimates.

RESULTS: 

The sensitivity and specificity of the PSMA PET/CT based miT-stage were 58% and 59% for pT3a-stage, 30% and 97% for ≥ pT3b-stage, and 68% and 61% for overall ≥ pT3-stage, respectively. No statistically significant differences in diagnostic accuracy were found between tracers. We found a substantial intra-observer agreement for PSMA PET/CT assessment of ≥ T3-stage (k 0.70) and ≥ T3b-stage (k 0.75), whereas the interobserver agreement for the assessment of ≥ T3-stage (k 0.47) and ≥ T3b-stage (k 0.41) were moderate.

CONCLUSION: 

In a large, multicentre study evaluating 600 patients with newly diagnosed intermediate and high-risk PCa, we showed that PSMA PET/CT may have a value in local tumour staging when pathological tumour stage in the radical prostatectomy specimen was used as the reference standard. The intra-observer and interobserver variability of assessment of tumour extent on PSMA PET/CT was moderate to substantial.

Original languageEnglish
Pages (from-to)1741-1752
Number of pages12
JournalEuropean Journal of Nuclear Medicine and Molecular Imaging
Volume51
Issue number6
Early online date26 Jan 2024
DOIs
Publication statusPublished - May 2024

Bibliographical note

Publisher Copyright:
© The Author(s) 2024.

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