Real-world evidence of the PRIMARY score: an Argentinian experience

Objective: The PRIMARY score incorporates intraprostatic prostate-specific membrane antigen (PSMA) uptake pattern and intensity to improve the detection of clinically significant prostate cancer. This study evaluated, in an Argentinian real-world cohort, whether intraprostatic maximum standardised uptake value (SUVmax) on [68Ga]Ga-PSMA PET/CT identifies clinically significant prostate cancer, defined as Gleason score ≥ 7 or ISUP grade group ≥ 2. Methods: We performed a retrospective observational multicentre study including patients evaluated between 2022 and 2026 who underwent [68Ga]Ga-PSMA PET/CT and had histopathological data available. Age, prostate-specific antigen, SUVmax, Gleason score and referring centre were recorded. Diagnostic performance for an exploratory SUVmax threshold was calculated using histopathology as the reference standard. Results Among 273 patients with histologically confirmed prostate cancer, 264 (96.7%) had clinically significant disease and 9 (3.3%) had Gleason 6 disease. All 187 patients with SUVmax ≥ 10.2 had Gleason score ≥ 7. The threshold showed sensitivity of 70.8%, specificity of 100%, positive predictive value of 100%, negative predictive value of 10.5%, diagnostic accuracy of 71.8% and an area under the receiver operating characteristic curve of 0.874. SUVmax differed significantly across ISUP grade groups (Kruskal-Wallis H = 32.03; p < 0.001). Conclusions In this real-world cohort, SUVmax ≥ 10.2 was exclusively associated with clinically significant prostate cancer. These findings support the SUVmax intensity component of the PRIMARY score as a potential non-invasive marker of tumour aggressiveness, requiring prospective validation. Clinical trial registration Not applicable this was a retrospective observational study.