Multicenter External Validation and Optimization of a Proposed Nomogram for Prostate-Specific Membrane Antigen PET/CT...

Area of Science:

• Nuclear Medicine
• Urologic Oncology
• Radiomics

Background:

• Prostate-specific membrane antigen (PSMA) PET/CT is the standard for imaging prostate cancer (PCa) biochemical recurrence (BCR).
• Limited availability necessitates patient selection criteria for PSMA PET/CT.
• A European nomogram was developed to predict PSMA PET/CT positivity in BCR patients.

Purpose of the Study:

• To externally validate the European PSMA PET/CT positivity prediction nomogram in a large regional cohort.
• To assess the nomogram's impact as a selective tool for PSMA PET/CT in BCR patients.
• To develop a novel, optimized nomogram for patient selection.

Main Methods:

• A multicenter, observational, retrospective study involving 413 patients with BCR after radical PCa treatment.
• Validation, calibration, and readjustment of the European PSMA PET/CT positivity prediction nomogram.
• Analysis of clinical/demographic data, PSMA PET/CT detection rates, variable associations, and nomogram accuracy (ROC, DCA).

Main Results:

• The original European nomogram showed low predictive ability (AUC 0.57).
• Independent predictors of positive PSMA PET/CT were PSA level (≥0.5 ng/dL) and PSA persistence.
• A novel, adjusted nomogram demonstrated significantly improved predictive ability (AUC 0.84) and clinical utility.

Conclusions:

• The European nomogram had limited predictive power in external validation.
• The novel, recalibrated nomogram shows moderate-to-high predictive ability.
• This optimized nomogram can enhance the selection of BCR patients eligible for PSMA PET/CT.