Validation of the PSMA PRIMARY scoring system and comparison to an E-PSMA Likert system for [68Ga]Ga-PSMA-11 PET/CT interpretation in men with suspected radiorecurrent prostate cancer
File(s)
Published version
Author(s)
Type
Journal Article
Abstract
Background:
To validate the recently published 5-point PRIMARY scoring system against a 5-point European Association of Nuclear Medicine (E-PSMA) Likert system for the detection of intraprostatic recurrence for patients undergoing [68Ga]Ga-PSMA-11 PET/CT who have previously received radiotherapy for prostate cancer as their primary treatment.
Patients and Methods:
Thirty-five patients from one centre were investigated for suspected radiorecurrence between 2016 and 2022. All patients underwent multiparametric MRI and [68Ga]Ga-PSMA-11 PET/CT for staging, then prostate biopsy. Analyses were performed at the hemi-gland level. Two expert readers, blinded to other clinical, pathologic, and radiologic data, independently assigned each hemi-gland an E-PSMA Likert and PRIMARY score. Outcomes were comparative diagnostic accuracy metrics and interreader agreement for each system at the hemi-gland level. Scores of 3–5 were considered suspicious for intraprostatic cancer.
Results:
Of 70 hemi-glands, 43 (61%) had cancer on biopsy. Area under the curve was high and not statistically significantly different between systems (E-PSMA Likert: 0.84; 95% CI: 0.74–0.92; PRIMARY: 0.82; 95% CI: 0.71–0.91; P = 0.7). Sensitivity for E-PSMA Likert was 0.89 (95% CI: 0.78–0.96), not statistically different compared with the PRIMARY system (0.79; 95% CI: 0.67–0.89; P = 0.3). Specificity for the E-PSMA Likert system was 0.67 (95% CI: 0.46–0.86), not statistically different compared with the PRIMARY system (0.78; 95% CI: 0.60–0.91; P = 0.1). There was substantial interreader agreement between each reader for both E-PSMA Likert (κ = 0.65; 95% CI: 0.44–0.83) and PRIMARY systems (κ = 0.74; 95% CI: 0.59–0.90).
Conclusions:
In patients with biochemical recurrence after primary radiotherapy for prostate cancer, both the 5-point PRIMARY and E-PSMA Likert scoring systems score demonstrated good performance and substantial interreader agreement between experts for the detection of intraprostatic recurrences.
To validate the recently published 5-point PRIMARY scoring system against a 5-point European Association of Nuclear Medicine (E-PSMA) Likert system for the detection of intraprostatic recurrence for patients undergoing [68Ga]Ga-PSMA-11 PET/CT who have previously received radiotherapy for prostate cancer as their primary treatment.
Patients and Methods:
Thirty-five patients from one centre were investigated for suspected radiorecurrence between 2016 and 2022. All patients underwent multiparametric MRI and [68Ga]Ga-PSMA-11 PET/CT for staging, then prostate biopsy. Analyses were performed at the hemi-gland level. Two expert readers, blinded to other clinical, pathologic, and radiologic data, independently assigned each hemi-gland an E-PSMA Likert and PRIMARY score. Outcomes were comparative diagnostic accuracy metrics and interreader agreement for each system at the hemi-gland level. Scores of 3–5 were considered suspicious for intraprostatic cancer.
Results:
Of 70 hemi-glands, 43 (61%) had cancer on biopsy. Area under the curve was high and not statistically significantly different between systems (E-PSMA Likert: 0.84; 95% CI: 0.74–0.92; PRIMARY: 0.82; 95% CI: 0.71–0.91; P = 0.7). Sensitivity for E-PSMA Likert was 0.89 (95% CI: 0.78–0.96), not statistically different compared with the PRIMARY system (0.79; 95% CI: 0.67–0.89; P = 0.3). Specificity for the E-PSMA Likert system was 0.67 (95% CI: 0.46–0.86), not statistically different compared with the PRIMARY system (0.78; 95% CI: 0.60–0.91; P = 0.1). There was substantial interreader agreement between each reader for both E-PSMA Likert (κ = 0.65; 95% CI: 0.44–0.83) and PRIMARY systems (κ = 0.74; 95% CI: 0.59–0.90).
Conclusions:
In patients with biochemical recurrence after primary radiotherapy for prostate cancer, both the 5-point PRIMARY and E-PSMA Likert scoring systems score demonstrated good performance and substantial interreader agreement between experts for the detection of intraprostatic recurrences.
Date Issued
2026-01-01
Date Acceptance
2025-09-08
Citation
Clinical Nuclear Medicine, 2026, 5 (1), pp.e1-e10
ISSN
0363-9762
Publisher
Lippincott, Williams & Wilkins
Start Page
e1
End Page
e10
Journal / Book Title
Clinical Nuclear Medicine
Volume
5
Issue
1
Copyright Statement
© 2025 The Author(s). Published by Wolters Kluwer Health, Inc. This is an open access article distributed under the Creative Commons Attribution License 4.0 (CCBY), which permits unre- stricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
License URL
Identifier
10.1097/RLU.0000000000006168
Subjects
PSMA PET/CT
prostate cancer
PRIMARY
radiotherapy
recurrence
Likert
Publication Status
Published