Racial disparities in all-cause mortality among younger commercially insured women with incident metastatic breast cancer.

Racial disparities in breast cancer mortality persist and are likely related to multiple factors. Over the past decade, progress has been made in treating metastatic breast cancer, particularly in younger women. Whether disparities exist in this population is unknown. Using administrative claims data between 2000 and 2011 (OptumInsight, Eden Prairie, MN) of members insured through a large national US health insurer, we identified women aged 25-64 years diagnosed with incident metastatic breast cancer diagnosed between November 1, 2000, and December 31, 2008. We examined time from diagnosis to death, with up to 3 years of follow-up. We stratified analyses by geocoded race and socio-economic status, age-at-diagnosis, morbidity score, US region of residence, urban/non-urban, and years of diagnosis. We constructed Kaplan-Meier survival plots and analyzed all-cause mortality using multivariate Cox proportional hazard models. Among 6694 women with incident metastatic breast cancer (78 % Caucasian, 4 % African American, and 18 % other), we found higher mortality rates among women residing in predominantly African American versus Caucasian neighborhoods (hazard ratio (HR) 1.84; 95 % confidence interval, CI 1.39-2.45), women with high versus lower morbidity (HR 1.30 [1.12-1.51]), and women whose incident metastatic diagnosis was during 2000-2004 versus 2005-2008 (HR 1.60 [1.39-1.83]). Caucasian (HR 0.61 [0.52-0.71]) but not African American women (HR not significant) experienced improved mortality in 2005-2008 versus 2000-2004. Despite insured status, African American women and women with multi-morbidity had poorer survival. Only Caucasian women had improved mortality over time. Modifiable risk factors for increased mortality need to be addressed in order to reduce disparities.