Prostate-specific membrane antigen (PSMA) positron emission tomography (PET) compared to computed tomography (CT) for advanced renal cell carcinoma (RCC).

4540 Background: There is emerging role of the use of PSMA PET in RCC. Herein, we report our experience in use of PSMA PET in recurrent or metastatic RCC in Brisbane, Australia. Methods: Patients (pts) who underwent PSMA PET and conventional diagnostic CT for metastatic or recurrent RCC between 2015 and 2020 at three institutions were identified. Retrospective chart reviews were conducted using standardized collection template. The outcomes included percentage of patients who had a change in management secondary to PSMA PET findings, comparison of metastasis detection for PSMA PET vs. CT, and biopsy histology of PSMA avid sites. Results: 42 PSMA PET were performed in 40 patients. 10 pts (25%) and 30 pts (75%) had PSMA PET in the metastatic disease and recurrent disease setting, respectively. Table 1 highlights demographics. Overall, 12 pts (30%, n=3 metastatic, n=9 recurrent) had a change in management following PSMA PET. In the metastatic disease group, 2 pts (20%) underwent initial systemic therapy (after histological confirmation) due to higher burden of disease shown with PSMA PET than CT, while systemic therapy was changed for 1 pt (10%). In the recurrent disease group, PSMA improved delineation of suspected recurrence (compared to CT) resulting in resection rather than surveillance (n=4; 13%) or change in surgical approach for resection (n=1; 3%). PSMA PET distribution showed more metastatic sites than CT leading to systemic therapy rather than resection of recurrence (n=2; 7%), while absent PSMA activity for suspected recurrence on CT led to surveillance rather than resection (n=2; 7%). PSMA PET detected more sites of metastases compared with conventional scan in 6 pts (60%) with metastatic disease and in 9 pts (30%) with recurrent disease. 26 pts had biopsy of PSMA avid sites. Majority of pts had confirmed recurrence of clear cell renal carcinoma (n= 22; 85%). Other histology included sarcomatoid renal cell carcinoma (n=2; 8%), carcinoid (n=1; 4%), and urothelial cancer (n=1; 4%). In 2 instances, biopsy/resection was performed of a suspected recurrence on CT that was not PSMA avid, and neither showed malignancy. Conclusions: PSMA PET detected more accurately metastatic and recurrent disease, with high pathological concordance, to result in change in management for 30% of patients. Prospective study is warranted to further investigate the utility of PSMA PET scan in advanced RCC.[Table: see text]