Advancing equity in breast cancer biomarker testing: An updated study on hospital settings and patient involvement.

e13751 Background: Building on previous research, this updated study delves deeper into the persistent disparities in breast cancer biomarker testing across hospital settings. It provides new insights by including emerging biomarkers such as Microsatellite Instability (MSI), HRD, AKT1, PTEN, PIK3CA, PD-L1, NTRK Fusion, and ESR-1. The study also further explores demographic differences and the role of patient/caregiver involvement, aiming to enhance understanding of how these factors influence testing disparities. Methods: Continuing from prior analysis, this updated retrospective study utilizes de-identified physician-reported patient data from the Ipsos Global Oncology Monitor (Dec 2024 - Nov 2025). It involves 434 treating oncologists reporting on patient record data online from 9,775 female BC patients under drug therapy in the US, categorized by treatment setting (urban: 4092, suburban: 4897, rural: 786). This research focuses on updating testing rates, patient demographics (mean age, menopausal status), and patient/caregiver engagement in decision-making by hospital setting. Participating oncologists saw a minimum number of cancer patients per month. Results: This updated analysis reaffirms and expands on prior findings, showing that testing rates for emerging biomarkers remain consistently higher in urban/suburban settings compared to rural settings. Specifically, Microsatellite Instability (MSI) testing was reported in 42% of urban/suburban settings versus 68% in rural settings. Comparably, patterns across other biomarkers like PIK3CA (67% vs. 47%) and NTRK Fusion (51% vs. 37%) were observed. Similar trends were seen when comparing emerging biomarker testing rates by hospital setting for HRD, AKT1, PTEN, PD-L1, and ESR1. Urban/suburban patients were younger (mean age 61.54) compared to rural (mean age 63.03) with a higher percentage of post-menopausal patients in rural areas (95% vs. 89%). In addition, patients/caregivers in urban/suburban settings were more proactive, with 39% researching treatment options or requesting specific treatments, compared to 29% in rural settings. Conclusions: Reinforcing earlier conclusions, this updated study highlights notable, continued disparities in biomarker testing and demographic factors across varied healthcare settings. It emphasizes the urgent need for education and policy reforms that promote equitable access to innovative biomarker tests and personalized treatment strategies. Furthermore, enhancing patient/caregiver involvement in treatment decisions remains crucial for addressing these disparities.