3323 - Prostate-Specific Membrane Antigen (PSMA) Imaging Practice Patterns and Association with Androgen Deprivation Therapy Usage: Results from a Prospective Statewide Radiation Therapy Quality Consortium
Presenter(s)
R. Rebernick1, H. Yin2, S. N. Regan3, M. P. Dykstra4, M. Grubb4, M. Zaki5, M. Mislmani6, W. McLaughlin1, D. Kendrick7, S. R. Miller II8, D. A. Dryden5, M. Khadija9, D. W. Litzenberg4, M. Mietzel4, V. Narayana10, D. K. Heimburger11, M. Schipper1, W. C. Jackson4, and R. T. Dess4; 1University of Michigan, Ann Arbor, MI, 2Department of Biostatistics, University of Michigan, Ann Arbor, MI, 3SUNY Upstate Medical University, Syracuse, NY, 4Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, 5Covenant HealthCare, Saginaw, MI, 6West Michigan Cancer Center, Kalamazoo, MI, 7Michigan Radiation Oncology Quality Consortium Coordinating Center, Ann Arbor, MI, 8Wayne State University, Detroit, MI, 9University of Michigan Health West, Wyoming, MI, 10Ascension Providence Hospital, Southfield, MI, 11Munson Healthcare, Traverse City, MI
Purpose/Objective(s): In December 2020, the FDA approved PSMA positron emission tomography (PET) imaging for men with prostate cancer. Compared to computed tomography and bone scan, PSMA-PET offers superior diagnostic accuracy; however, its utilization and influence on planned androgen deprivation therapy (ADT) with curative-intent radiotherapy remain unknown. Given this rapidly evolving landscape, we leveraged a prospective statewide consortium to analyze current PSMA-PET trends and their association with ADT use in contemporary practice.
Materials/Methods: Patients enrolled in the statewide consortium with non-metastatic, Gleason grade group 3-5 prostate cancer were included; those with M1 disease were excluded. Clinical and treatment variables were collected prospectively using standardized forms, including diagnostic imaging, radiotherapy details, and ADT intent, type, and duration. The primary outcome was PSMA-PET staging utilization. Secondary analyses assessed associations between PSMA-PET staging and guideline-concordant ADT (18-36 months, “GC ADT”) in the high-risk/N1 cohort using multivariable analysis (MVA) adjusted for treatment facility, T-stage, Gleason grade group, and PSA.
Results: Between 04/01/2021 and 11/30/2024, 1,023 patients from 26 centers met inclusion criteria. Overall, 352 patients (34%) underwent PSMA-PET staging, including 238 of 511 (47%) with high-risk disease. Utilization increased annually (0% in 2021 to 59% in 2024 among all patients, and 0% to 74% in the high-risk cohort; both p-trend <0.01). Rates of guideline-concordant ADT in the high-risk/N1 cohort were similar between those staged with PSMA-PET (164/228, 72%) and those without (176/268, 66%; p=0.13). On MVA, PSMA-PET use was not significantly associated with guideline-concordant ADT (OR 1.2 [0.7-2.1], p=0.45). Among PSMA-staged high-risk patients, 50 of 232 (22%) had pelvic lymph node-positive disease, with higher GC ADT utilization in PSMA node-positive cases versus node-negative (85% vs. 68%, p=0.02). In MVA, pelvic lymph node positivity remained a significant predictor of GC ADT use (OR 2.4 [1.1-5.4], p=0.04).
Conclusion: PSMA-PET utilization has increased dramatically within a statewide consortium, with three-fourths of high-risk patients undergoing molecular imaging in 2024. Guideline-concordant ADT rates were similar regardless of staging imaging modality. However, within the PSMA-staged cohort, pelvic lymph node positivity was associated with a two-fold increase in GC ADT use. Ongoing trials, such as NRG GU009 (NCT04513717), which incorporate PSMA-based staging, may better define the optimal ADT duration as molecular imaging becomes more integrated into clinical practice.