S. R. Miller1,2, R. Tucker3, W. C. Jackson1, M. E. Caram4,5, P. A. Tsao4,5, K. D. Stensland6,7, D. A. Elliott1,2, M. Green1,2, M. Schipper3, R. T. Dess1, and A. K. Bryant1,2; 1Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, 2Department of Radiation Oncology, Veterans Affairs Ann Arbor Health System, Ann Arbor, MI, 3Department of Biostatistics, University of Michigan, Ann Arbor, MI, 4Division of Medical Oncology, Department of Medicine, Veterans Affairs Ann Arbor Healthcare System, Ann Arbor, MI, 5Division of Hematology/Oncology, Department of Medicine, University of Michigan, Ann Arbor, MI, 6Department of Urology, University of Michigan, Ann Arbor, MI, 7Section of Urology, Veterans Affairs Ann Arbor Healthcare System, Ann Arbor, MI
Purpose/Objective(s): In September 2021, National Comprehensive Cancer Network (NCCN) Guidelines were updated to allow prostate specific membrane antigen (PSMA) PET staging for newly diagnosed unfavorable intermediate-risk (UIR), high-risk (HR), or very high-risk (VHR) prostate cancer. Subsequent uptake of staging PSMA PET and positivity rates are unknown. Materials/
Methods: We identified all newly diagnosed prostate cancer cases in the national Veterans Health Administration (VHA) from January 2020 to August 2023. Staging PSMA scans within +/- 90 days of prostate cancer diagnosis were identified using VHA radiology data and linked records from non-VHA providers. Gleason score (GS) was identified by a validated natural language processing algorithm. Initial PSA and TNM stage were collected through VHA electronic medical record data; missing stage variables were imputed. The proportion of patients undergoing PSMA staging over time was quantified by GS and PSA. We performed manual chart review of 2,024 staging PSMA scan reports performed within VHA to assess PSMA positivity rates by NCCN risk group defined by conventional imaging. Results: We identified 35,440 patients with newly diagnosed prostate cancer, of whom 4,562 underwent PSMA staging. Median age was 69; 56% identified as White and 36% Black. The proportion of patients undergoing PSMA staging began increasing in all groups in early 2021 and continued to increase through the end of the study period. In the last 6 months of the study period (2/2023 to 8/2023), the proportion of patients with PSMA staging by GS/PSA was 3.1% (GS6, PSA<10), 16.0% (GS6, PSA 10-20 or GS3+4, PSA<10), 45.6% (GS4+3, PSA<20 or GS 3+4, PSA 10-20), 60.9% (GS 8-10 or PSA>20), and 66.1% (GS 8-10 and PSA>20). Among patients who were N0/M0 by conventional imaging, PSMA positivity rates (N1 and/or M1) were 0% (0/17, low risk [LR]), 1.5% (3/195, favorable intermediate risk [FIR]), 4.0% (20/490, UIR), 11% (76/690, HR), and 29% (106/370, VHR). Rates of nodal disease only (PSMA N1/M0) were 1.5% in FIR, 1.0% in UIR, 7.1% in HR, and 12.2% in VHR. Rates of oligometastatic disease (1-5 PSMA positive distant metastases, with or without nodal disease) were 0% in FIR, 2.7% in UIR, 2.9% in HR, and 9.7% in VHR. Rates of widespread metastases (>10 PSMA metastases) were 0% in FIR, 0% in UIR, 0.1% in HR, and 3.3% in VHR. Conclusion: Rates of PSMA staging for newly diagnosed prostate cancer increased from 2020-2023 in the VHA, including among patients meeting FIR criteria by GS and PSA. Overall nodal or distant positivity rates among FIR and UIR patients were low (<5%). Optimal resource allocation may require reconsideration of routine PSMA staging for all UIR patients and efforts to decrease PSMA staging for FIR patients.
