THE IMPACT OF 68GA-PSMA PET/CT ON THERAPY MANAGEMENT OF HIGH RISK PROSTATE CANCER

Objective: We evaluated the impact of 68Ga-PSMA PET/CT (PSMA PET) on therapy management of newly diagnosed highrisk prostate cancer (PCa). Material and Method: Patients who underwent a PSMA PET for primary staging of high-risk PCa were evaluated retrospectively. Patients had abdominopelvic CT (n=126), pelvic MRI (n=42) and bone scintigraphy (BS) (n=40) prior to PSMA PET. All clinical, biochemical, and imaging data were documented. Increased PSMA uptakes related to PCa were documented according to previously described PSMA-RADS version 1.0 based on a fivepoint scale. The impact of PSMA PET on patient management was evaluated through pre and post PET/CT questionnaires, retrospectively. Management changes were categorized as inter or intramodality change, based on PSMA PET results. Paired samples t-test was used to compare subgroups in SPSS version 24.0 software. A p-value <0.05 was considered significant. Results: A total of 126 patients were included in the study. The median PSA level was 30.8 ng/ml (95%CI: 2.1-268.6 ng/ml) and median GS was 8 (range: 6-10). Based on the PSMA PET findings, 41 patients (32.5%) had more extensive disease and 2 patients (1.6%) had less extensive disease. Overall, therapy management was changed in 38 patients (30.1%). Intermodality changes occurred in 29 patients (23%), and intramodality changes occurred in 9 patients (7.1%). The change in management was similar in patients with BS and without BS, 30% vs. 30.2%. Conclusion: PSMA PET impacted the therapy management in almost one-third of patients in high-risk PCa even though they had already been staged with standard imaging modalities.