Introduction: PSMA PET/CT has become the gold standard in clinical practice for whole-body re-staging of intermediate to high-risk prostate cancer (PCa). Its application in primary diagnosis has also been suggested. The objective of our study was to investigate PSMA PET/CT performance in predicting local staging and pathological grading prior to radical surgery, with the aim of tailoring the surgical approach according to disease characteristics. Methods: We retrospectively reviewed prospectively collected data of patients referred to our tertiary-care center from October 2020 to August 2022. All of them performed primary staging PSMA PET/CT and the primary treatment was robot assisted radical prostatectomy (RARP) with or without lymph node dissection (LND). The Standard Uptake Value max of primary tumour (SUV max) and tumour to background ratio (SUV ratio) were reported. We evaluated the relationship between SUV max and SUV ratio with pathological tumour (pT) staging and International Society for Urological Pathology (ISUP) grade. The Cochran-Armitage test for trend was used to assess the relationship between SUV values and PCa stage and grade. Results: Overall, 179 pts were included; mean age was 66 (IQR 60-71) and 38 (21.23%) pts had PCa family history. Mean PSA was 7.07 (5.44- 11.95) ng/ml. According to European Association of Urology risk groups, 109 (61%) pts were low/intermediate risk and 70 (39%) were high risk. LND was performed in 134 (74.86%) pts. Mean SUV max and SUV ratio significantly increased from 5.3 (4.2-10.8) and 12 (7-20) in pT2a to 9.9 (6.9-18.5) and 20 (12-53) in pT3b patients, respectively (all p < 0.001); mean SUV max and SUV ratio increased from 5.9 (5.3-67) and 9 (4-14) in ISUP 1 PCa to 11.9 (5.5-19.3) and 33 (17-53) in ISUP 5 PCa, respectively (all p < 0.001). Similarly mean SUV max and SUV ratio increased from 6.82 (4.29-11.94) and 14 (10-30) in organ confined disease to 14.28 (7.1-22.88) and 29 (14-58) in non-organ confined disease, respectively (all p <0.001). Conclusions: According to our results, both pT stage and ISUP grade appear to be significantly associated both with tumor stage and grade. In consequence, PSMA PET/CT could be useful for the pre-treatment risk stratification of PCa individuals and may be adopted in the treatment decision-making process of these individuals. SOURCE OF Funding: None
