Abstract PS5-01-06: Contribution of Sociodemographic Characteristics to Treatment Delays in Patients with de novo Metastatic HER2-Positive Breast Cancer

Abstract Background: Outcomes for patients with de novo metastatic human epidermal growth factor receptor 2 (HER2)-positive breast cancer have dramatically improved due to advances in HER2-directed therapy, yet significant disparities persist, with Black and Hispanic patients presenting with more advanced stage disease and experiencing worse survival outcomes compared to White patients. Studies suggest racial and ethnic minorities experience longer delays in treatment initiation, however large, comprehensive analyses of the impact of sociodemographic and clinical factors at the national level in the U.S. remain limited. Methods: We retrospectively identified patients diagnosed with de novo metastatic HER2-positive breast cancer between 2010 and 2022 using the National Cancer Database (NCDB). Clinical and sociodemographic characteristics were collected and compared across racial and ethnic groups. We categorized systemic therapy as chemotherapy alone or chemotherapy plus HER2-directed therapy. Treatment receipt and time to treatment initiation were evaluated by race/ethnicity. Multivariable linear regression was performed to examine sociodemographic differences in time to initiation of systemic and localized (i.e., radiotherapy) therapies, respectively. Beta coefficients reflected adjusted differences in treatment timing, with 95% confidence intervals (95% CI) reported. Results: A total of 27,972 patients with de novo metastatic HER2-positive breast cancer were included. Mean age was 58.8 years; 69.0% were White, 17.5% Black, 7.8% Hispanic, and 4.6% Asian/Pacific Islander (per self-report). At initial presentation, 9.5% had brain metastases, and 58.2% had visceral metastases. At the time of diagnosis, Black and Hispanic patients were younger, more often uninsured or Medicaid-insured, and more likely to reside in lower-education, lower-income areas (p