Association between prostate specific membrane antigen imaging and initial treatment for prostate cancer among commercial insurance beneficiaries.

577 Background: Prostate specific membrane antigen positron emission tomography (PSMA-PET) increases the detection of metastatic prostate cancer relative to conventional imaging. To understand whether PSMA-PET is associated with greater use of therapies for metastatic disease we evaluated initial treatment among contemporary commercial insurance beneficiaries undergoing staging evaluation for prostate cancer. Methods: We conducted a retrospective cohort study among Blue Cross Blue Shield insurance beneficiaries with an incident diagnosis of prostate cancer from July 1st, 2021, through March 31, 2023, who received either PSMA-PET or bone scintigraphy imaging in the six-month period before and after diagnosis based on billing codes. The primary study outcome was the receipt of androgen pathway receptor inhibitor (ARPI) therapy in the one-year period following diagnosis using national drug codes. Secondary outcomes included local therapy and androgen deprivation therapy (ADT) use. Chi-square (χ²) tests were used to compare distributions of treatment by imaging modality. We used mixed effects logistic regression to examine the association between imaging modality (PSMA-PET versus bone scan) and initial treatment, accounting for beneficiary age, diagnosis period, comorbidity, frailty, local therapy, census region, and social deprivation index for clustering of beneficiaries within hospital referral regions. Results: Among 4,952 beneficiaries newly diagnosed with prostate cancer, 3,690 received bone scans and 1,262 received PSMA-PET imaging. The median age in both groups was 62 years. Patients receiving PSMA-PET were less likely to undergo radical prostatectomy. (40.8% versus 48.1%, χ² p<0.001) than beneficiaries imaged with bone scan. Receipt of ARPI was more common among beneficiaries who received a PSMA-PET scan (25.0%) versus bone scan (9.7%, χ² p<0.001). ADT use was also more common in PSMA-PET imaged versus bone scan imaged individuals (58.9% versus 39.4%, χ² p<0.001). PSMA-PET was independently associated with use of initial ARPI therapy, (odds ratio vs bone scan: 3.83, 95% confidence interval 3.11-4.71, p<0.001). Conclusions: In this claims-based study of a single large U.S. commercial health insurer, receipt of PSMA-PET was associated with increased use of therapies for metastatic prostate cancer. These findings highlight the growing role of molecular imaging in the diagnostic landscape of prostate cancer, and support further efforts to estimate effects of imaging on clinical outcomes and healthcare costs.