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.