Clinical, sociodemographic, and facility-related determinants of immunotherapy use in metastatic triple-negative breast cancer.

1105 Background: Immunotherapy has emerged as a promising treatment option for metastatic triple-negative breast cancer (mTNBC), yet the factors influencing its adoption remain poorly understood. This study investigates the clinical, sociodemographic, and facility-related determinants of immunotherapy use in patients with mTNBC from 2015 to 2020, utilizing data from the National Cancer Database (NCDB). Methods: We conducted a retrospective cohort study of mTNBC patients from the NCDB between 2015 and 2020, categorizing them into two groups: those who received immunotherapy and those who did not. Patients were excluded if they had missing data on key variables such as immunotherapy receipt and clinical characteristics (e.g., tumor stage, subtype). Univariable and multivariable logistic regression analyses were performed to identify factors influencing immunotherapy adoption. The impact of immunotherapy on overall survival was assessed using Cox proportional hazards regression analysis. Overall survival between the two groups was compared using the log-rank test. Results: A total of 1,887 mTNBC patients were included in the study: 1,656 (87.8%) did not receive immunotherapy, and 232 (12.2%) received immunotherapy. Multivariable logistic regression identified several factors associated with immunotherapy use. Later year of diagnosis (2018-2020: OR 5.35, p < 0.001) and academic facilities (OR 1.43, p = 0.044) were positively associated with immunotherapy use. In contrast, older age (71+: OR 0.49, p = 0.019), facilities in rural areas (OR 0.43, p = 0.042), Black race (OR 0.73, p = 0.039), Hispanic ethnicity (OR 0.53, p = 0.026), and higher Charlson comorbidity scores (OR 0.31, p = 0.035 for scores ≥2) were associated with a lower likelihood of receiving immunotherapy. Insurance status did not significantly influence immunotherapy use. Log-rank test showed that patients receiving immunotherapy had significantly improved survival compared to those who did not (Figure 1). The median survival for patients receiving immunotherapy was 2.21 years (95% CI: 1.80–2.96), compared to 1.01 years (95% CI: 0.93–1.11) for those not receiving immunotherapy (log-rank p < 0.001). Cox regression analysis showed that immunotherapy use was associated with a significantly reduced risk of death (HR 0.59, 95% CI: 0.46–0.77, p < 0.001). Conclusions: Immunotherapy use in mTNBC has increased in recent years, with clinical, sociodemographic, and facility-related factors influencing its adoption. Patients receiving immunotherapy had significantly better survival outcomes. Our findings highlight the importance of addressing disparities in access to immunotherapy, particularly related to race, age, ethnicity, and comorbidity burden, to ensure equitable treatment and outcomes for all mTNBC patients.