Disparities in treatment delays among metastatic breast cancer patients: insights from nationwide electronic health records, 2011-2022

Purpose: While previous research has highlighted treatment delay inequities in early-stage breast cancer and identified potential contributing factors, there is limited research on disparities in treatment delays for metastatic breast cancer (MBC). This study investigates these disparities in MBC treatment initiation, aiming to identify key factors crucial for improving timely access to care.

Method: Nationwide Flatiron Health electronic health records-derived deidentified database, including females aged 18+ diagnosed with either De novo or relapsed MBC in the U.S. between 2011 and 2022. Treatment delay, defined as > 60 days between diagnosis and first-line treatment, was assessed as a binary variable. T-tests and chi-squared tests analyzed patient characteristics (age, race, insurance, diagnosis stage, metastasis site, phenotypes, etc.) among delayed and non-delayed groups. Logistic regression evaluated the association between clinical and non-clinical factors and treatment delays.

Results: Among 20,617 patients with MBC, nearly 27% experienced treatment delays. These patients were generally younger, uninsured, historically marginalized, and newly diagnosed. Risk ratio analysis showed patients with only Medicare without secondary coverage (RR: 2.34, 95% CI [1.06, 5.16]) and uninsured (RR: 2.18, 95% CI [1.01, 4.76]) had higher risk of delays compared to those with commercial insurance. Historically marginalized patients had higher delay risk, ranging from 6% for Black patients to 12% for patients with not documented race/ethnicity background (p = 0.03) compared to White patients."

Conclusion: Our study highlights significant disparities in MBC treatment delays. Patients from historically marginalized groups and those without health insurance coverage or with only Medicare coverage are highly likely to experience delays. Addressing these disparities is essential for equitable healthcare and improved outcomes.