Trends and Disparities in the Use of Immunotherapy for Triple-Negative Breast Cancer in the US.

Importance: Triple-negative breast cancer (TNBC) disproportionately affects Black women. Immunotherapy improves outcomes in early-stage TNBC (esTNBC) and metastatic TNBC (mTNBC). However, racial and ethnic disparities in immunotherapy receipt and its potential association with oncologic outcomes are unknown. Objective: To examine trends and racial and ethnic disparities in immunotherapy receipt and differences in pathologic complete response (pCR) and overall survival (OS) in TNBC. Design, Setting, and Participants: This retrospective cohort study analyzed the 2019-2021 National Cancer Database. Data were analyzed from April 1 to August 31, 2024. The esTNBC cohort included patients with stage II to III TNBC treated with neoadjuvant therapy in 2021. The mTNBC cohort included patients with stage IV TNBC treated from 2019 to 2021, with all patients having received chemotherapy with or without immunotherapy. Main Outcomes and Measures: Immunotherapy use, pCR, and OS with respect to race and ethnicity. Results: A total of 10 724 patients with TNBC were included (mean [SD] age, 56.1 [13.7] years; 473 [4.4%] Asian or Pacific Islander, 2569 [24.0%] Black, 981 [9.1%] Hispanic, 6465 [60.3%] White, and 236 [2.2%] other). Immunotherapy use increased from 5.5% in 2017 to 38.8% in 2021 for mTNBC and from 4.2% in 2017 to 48.0% in 2021 for esTNBC. Of 7655 cases of esTNBC diagnosed in 2021, immunotherapy use was lower in Black patients (788 of 1715 [45.9%]), but this difference was not significant after adjusting for insurance status, treatment facility type, and other key variables. Among patients with esTNBC receiving immunotherapy, pCR was similar by race and ethnicity. Of 3069 cases of mTNBC diagnosed from 2019 to 2021, immunotherapy use was higher in Asian or Pacific Islander patients (36 of 97 [37.1%]) and lower in Black patients (238 of 848 [28.1%]). Black patients had lower odds of immunotherapy receipt than White patients (adjusted odds ratio, 0.63; 95% CI, 0.49-0.80) even after controlling for confounders. Among patients receiving immunotherapy, OS was similar between Black and White patients (adjusted hazard ratio, 0.92; 95% CI, 0.64-1.32). Conclusions and Relevance: In this cohort study of TNBC, Black patients with mTNBC were less likely to have received immunotherapy, even after controlling for socioeconomic factors. In both esTNBC and mTNBC cohorts, patients who received immunotherapy attained similar outcomes across racial and ethnic groups; thus, efforts should be made to ensure equal access to immunotherapy.