Prediction of upgrading in clinically insignificant prostate cancer patients undergoing radical prostatectomy: the value of Ga-68-PSMA PET/CT

OBJECTIVES: To evaluate the role of clinical and pathological variables, multiparametric magnetic resonance imaging (mpMRI), and Ga-68-PSMA PET/CT in prediction upgrading in patients who underwent radical prostatectomy (RP) for clinically insignificant prostate cancer (ciPCa). METHODS: Patients with The International Society of Urological Pathology (ISUP) grade group(GG) 1 by biopsy (bISUP GG 1) who underwent Ga-68-PSMA PET were reviewed. 38 who did not upgrade after RP were defined as group 1, and 37 who were upgraded after RP were defined as group 2. RESULTS: In patients with bISUP GG 1, the upgrade detection rate of the ISUP GG on RP material was 49.3%. PI-RADS 3, 4, and 5 scores were 71.1%, 18.4%, and 2.6% in group 1, respectively, whereas 51.4%, 18.9%, and 29.7% in group 2, respectively (p = 0.002). Mean index lesion diameter on mpMRI (p = 0.007) were found to be higher in patients who upgraded. The SUVmax detected on Ga-68-PSMA PET/CT was 4.65 in group 1 and 7 in group 2 (p = 0.003). ROC curve analysis provided a cut-off value of 4.6 g/mL for the SUVmax that would predict upgrading. PI-RADS 4-5 lesions on mpMRI (OR : 3.354,95% CI : 1.124-10.007, p = 0.030) and SUVmax ≥ 4.6 on PSMA PET/CT (OR : 6.113,95%CI : 1.893-19.875, p = 0.002) were found to be predictors for upgrading in multivariate analysis. CONCLUSIONS: Ga-68-PSMA PET/CT was found to be a potentially useful imaging biomarker for predicting pathological upgrading from combined systematic biopsy and mpMRI- targeted biopsy to RP. ADVANCES IN KNOWLEDGE: For patients with ciPCa, there is a high likelihood of risk reclassification if they have PI-RADS 4-5 score and SUVmax higher than 4.6 on Ga-68-PSMA PET/CT.