The impact of F-18 PSMA PET imaging on clinical decision-making in prostate cancer across disease states.

Abstract

63 Background: Piflufolastat F-18 (18F-DCFPyL) PSMA PET imaging was recently approved by the FDA for initial staging, biochemical recurrence (BCR), and restaging of metastatic prostate cancer. Given that the PSMA PET is a next-generation novel imaging modality that carries a higher sensitivity for detecting metastatic disease compared with conventional imaging, we aimed to assess how its integration into clinical care may have impacted the management of patients. Methods: We identified 236 patients who underwent an 18F-DCFPyL PET scan at the University of Minnesota between August 2021 to June 2022. The median PSA at the time of imaging was 1.75 ng/ml (range, 0.02 - 3740 ng/ml). All PSMA PET scans were evaluated by an experienced nuclear medicine physician. Descriptive statistics were used to analyze its impact on the clinical care of 158 patients: 22 for initial staging, 110 with biochemical recurrence, and 26 patients with known metastatic disease. The remaining 78 patients had no information available to assess clinical utility. Results: Metastatic PSMA-avid lesions were detected in 152/236 (64.4%) patients. In patients undergoing initial staging of high-risk prostate cancer, 17/40 (42.5%) patients had metastatic lesions outside the prostate involving 10 regional and 5 non-regional lymph nodes, 1 visceral site, and 10 bone metastases. 17/40 (42.5%) of the scans were unremarkable. 6/40 (15%) had equivocal scan results. For the patients with available clinical information, 12/22 (54.5%) had a change in their treatment plan post-DCFPyL, while 10/22 (45.5%) had no change. In the biochemical recurrence cohort, 93/151 (61.6%) had positive lesions: 28 local recurrences, 47 regional and 22 non-regional lymph nodes, 5 visceral and 28 bone metastases. Equivocal and negative scans accounted for 13/151 (8.6%) and 45/151 (29.8%) cases, respectively. 44/110 (40%) of the patients with clinical information had a change in their treatment plan, while the plan did not change for 66/110 (60%) cases. In patients with known metastatic prostate cancer undergoing restaging, 42/45 (93.3%) had DCFPyL-positive lesions; 12 local recurrences, 20 regional and 16 non-regional, 9 visceral, and 29 bone metastases. Equivocal and negative scans accounted for 2/45 (4.4%) and 1/45 (2.2) of cases, respectively. Only 11/26 (42.3%) of those with clinical information had their tentative treatment plan adjusted post-DCFPyL. No change in the treatment plan was made in 15/26 (57.7%) cases. Conclusions: Integration of the F-18 PSMA PET imaging substantially impacted clinical decision-making, especially for initial staging of high-risk localized disease (treatment change in 55%) and for biochemical recurrence (treatment change in 40%). It remains to be seen if this would translate into superior survival outcomes.