6525 Background: Inadequate access to healthcare services is associated with worse outcomes. Disparities in access to cancer care are more frequently seen among racial/ethnic minorities, uninsured patients, and those with low socioeconomic status. A provision in the Affordable Care Act called for expansion of Medicaid eligibility in order to cover more low-income Americans. In this study, we evaluate the impact of Medicaid expansion in 2-year mortality among metastatic BC patients according to race. Methods: Women (aged 40-64) diagnosed with metastatic BC (stage IV de novo) between 01/01/2010 and 12/31/2015 and residing in states that underwent Medicaid expansion in 01/2014 were identified in the National Cancer Database. For comparison purposes, 2010-2013 was considered the pre-expansion period and 2014-2015 the post-expansion period. We calculated 2-year mortality difference-in-difference (DID) estimates between White and non-White patients using multivariable linear regression models. Results are presented as adjusted differences (in % points) between groups in the pre- and post-expansion periods and as adjusted DID with 95%CI. Covariates included age, comorbidity, BC subtype, insurance type, transfer of care, distance to hospital, region, residence area, education, income quartile, facility type and facility volume. In addition, overall survival (OS) was evaluated in pre- and post-expansion periods via Kaplan-Meier method and Cox proportional hazards models; results are presented as 2-year OS estimates, hazard ratios (HRs), and 95% CIs. Results: Among 7,675 patients included, 4,942 were diagnosed in the pre- and 2,733 in the post-expansion period. We observed a reduction in 2-year mortality rates in both groups according to Medicaid expansion. Among Whites 2-year mortality decreased from 42.5% to 38.7% and among non-Whites from 45.4% to 36.4%, resulting in an adjusted DID of -5.2% (95%CI -9.8 to -0.6, p = 0.027). A greater reduction in 2-year mortality was observed among non-Whites in a sub-analysis of patients who resided in the poorest quartile (n = 1372), with an adjusted DID of -14.6% (95%CI -24.8 to -4.4, p = 0.005). In the multivariable Cox model, during the pre-expansion period there was an increased risk of death for non-Whites compared to Whites (HR 1.14, 95% CI 1.03 to 1.26, P = 0.04), however no differences were seen in the post-expansion period between the two groups (HR 0.93, 95% CI 0.80 to 1.07, P = 0.31). Conclusions: Medicaid expansion reduced racial disparities by decreasing the 2-year mortality of non-White patients with metastatic breast cancer and reducing the gap when compared to Whites. These results highlight the positive impact of policies aimed at improving equity and increasing access to health care.
117PD_PR Survival benefit of surgical removal for the primary tumor in stage IV breast cancer patients