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

Purpose: Immunotherapy has emerged as a promising treatment for metastatic triple-negative breast cancer (mTNBC), yet factors influencing its adoption remain unclear. This study examines clinical, sociodemographic, and facility-related determinants of immunotherapy use in mTNBC patients using the National Cancer Database (NCDB).

Methods: We conducted a retrospective cohort study of mTNBC patients from the NCDB (2015-2020), categorizing them into immunotherapy recipients and non-recipients. Patients with missing data on key variables were excluded. Univariable and multivariable logistic regression identified factors influencing immunotherapy adoption. Cox proportional hazards regression and log-rank tests assessed overall survival.

Results: Among 1,887 mTNBC patients, 232 (12.2%) received immunotherapy. Factors positively associated with immunotherapy use included later diagnosis year (2018-2020: OR 5.35, p < 0.001), academic facilities (OR 1.43, p = 0.044), and private insurance (OR 1.34, p < 0.001). Lower likelihood of immunotherapy use was observed in older age (71+: OR 0.49, p = 0.019), rural facilities (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 (≥ 2: OR 0.31, p = 0.035). Immunotherapy was associated with significantly improved survival (median 2.21 vs. 1.01 years, log-rank p < 0.001) and reduced mortality risk (HR 0.59, p < 0.001).

Conclusion: Immunotherapy use in mTNBC has increased in recent years, with clinical, sociodemographic, and facility-related factors influencing its adoption. Our findings highlight the importance of addressing disparities in access to immunotherapy to ensure equitable treatment and better survival outcomes for all mTNBC patients.