TOPLINE:

Black and Hispanic patients with de novo metastatic breast cancer (dnMBC) experience significant delays in treatment initiation across all subtypes compared with White patients. Among 117,743 patients, Black patients faced 6.6-day delays in endocrine therapy and 11.3-day delays in radiotherapy for hormone receptor (HR)-positive disease, while Hispanic patients experienced delays of 8.3 days and 18.6 days, respectively.

METHODOLOGY:

• Patients from minoritized racial and ethnic groups generally receive diagnoses at later stages of BC, face care barriers, and experience worse outcomes, despite advances in screening and treatment, with limited data on disparities in presentation and treatment initiation timing for dnMBC nationally.
• Black women are more likely than White women to present with dnMBC even after accounting for socioeconomic status, frequently present with more aggressive subtypes such as TNBC, and have higher odds of brain, bone, and liver metastases.
• Researchers conducted a retrospective cross-sectional analysis of 117,743 female patients diagnosed with dnMBC between 2010 and 2022 using the National Cancer Database in the US, evaluating presentation and treatment differences across 3 main subtypes: HR-positive and epidermal growth factor receptor 2 (ERBB2)-negative, ERBB2-positive, and triple-negative BC (TNBC).
• Patients were categorized by race and ethnicity into Asian or Pacific Islander (4271 patients, 3.7%), Black (20,153 patients, 17.3%), Hispanic (7785 patients, 6.7%), and White (83,337 patients, 71.3%) groups, with mean age of 62.0 years.
• Metastatic sites at initial diagnosis were classified as brain, bone only, or visceral (liver and/or lung), and treatment modalities included chemotherapy, endocrine therapy, ERBB2-directed therapy, immunotherapy, and radiotherapy.
• Treatment initiation timing was defined as days between diagnosis and treatment start, modeled using multiple linear regression with adjustment for age, histologic subtype, comorbidity index, insurance status, education level, income, and facility type.
• Data were analyzed from March to September 2025, following Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) reporting guidelines.

TAKEAWAY:

• Among patients with HR-positive, ERBB2-negative dnMBC, Black patients experienced significantly longer times to endocrine therapy initiation (beta coefficient, 6.6; 95% CI, 4.5-8.8), chemotherapy (beta coefficient, 3.6; 95% CI, 1.4-5.8), and radiotherapy (beta coefficient, 11.3; 95% CI, 5.9-16.7) than White patients in fully adjusted models.
• For ERBB2-positive disease, Black patients had delays in ERBB2-directed therapy initiation (beta coefficient, 5.7; 95% CI, 2.9-8.6) and chemotherapy (beta coefficient, 5.1; 95% CI, 0.1-10.1), while Hispanic patients experienced a 7.3-day delay (95% CI, 3.2-11.4) in ERBB2-directed therapy and a 15.6-day delay (95% CI, 8.1-23.0) in chemotherapy.
• In TNBC, Black (beta coefficient, 7.8; 95% CI, 0.6-15.1) and Hispanic (beta coefficient, 16.6; 95% CI, 6.0-27.2) patients experienced longer times to immunotherapy initiation in age-adjusted models, but these differences were no longer significant after socioeconomic covariate adjustment.
• Across all subtypes, Medicaid enrollment, Medicare enrollment, and lack of insurance were associated with delayed treatment initiation, with living in areas with lower income and education levels also linked to heterogeneous delays across treatment modalities.

IN PRACTICE:

“This cross-sectional study of patients with dnMBC found racial and ethnic disparities in disease presentation and inequities in timely treatment for dnMBC across subtypes, emphasizing the need for tailored interventions to improve care delivery and outcomes,” wrote the authors of the study.

SOURCE:

The study was led by Jincong Q. Freeman, MPH, MS, Department of Public Health Sciences, University of Chicago, Chicago, and Rita Nanda, MD, Section of Hematology and Oncology, Department of Medicine, University of Chicago Medicine, Chicago. It was published online on April 23 in JAMA Network Open.

LIMITATIONS:

Given the retrospective design, underreporting and misclassification are possible. The National Cancer Database does not collect incident and recurrent metastatic cases, precluding differentiation between metastasis development and recurrence. Unmeasured factors such as marital status, genetics, and genomics could better explain the observed treatment initiation disparities. Area-level educational attainment, household income, and rural-urban residence were derived from the registry without individual zip codes, preventing accounting for clustering and requiring interpretation as contextual rather than individual-level effects. The database lacks details regarding specific treatment regimens and reasons for treatment delays, preventing distinction between patient-level, practitioner-level, and other system-level factors. The patient cohorts may not be representative of all patients with dnMBC in the US, limiting the generalizability of the study findings.

DISCLOSURES:

This study received support in part from the Breast Cancer Research Foundation (BCRF-23-071), the National Cancer Institute (P20CA233307), and the National Institute on Aging (T32AGO000243). Freeman disclosed receiving grants from Susan G. Komen (TREND21675016) during the conduct of the study. Nanda disclosed receiving personal fees from multiple pharmaceutical companies including Arvinas, AstraZeneca, Corcept Therapeutics, Daiichi Sankyo, Exact Sciences, GE, Gilead, Guardant Health, Lilly, Mabwell, Merck, Moderna, Novartis, Pfizer, Stemline, and Summit Therapeutics, and grants from several companies paid to her institution outside the submitted work. Additional disclosures are noted in the original article.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.