Association of Medicaid Expansion Under the Affordable Care Act With Breast Cancer Stage at Diagnosis.

Importance: The expansion of Medicaid sought to fill gaps in insurance coverage among low-income Americans. Although coverage has improved, little is known about the relationship between Medicaid expansion and breast cancer stage at diagnosis. Objective: To review the association of Medicaid expansion with breast cancer stage at diagnosis and the disparities associated with insurance status, age, and race/ethnicity. Design, Setting, and Participants: This cohort study used data from the National Cancer Database to characterize the relationship between breast cancer stage and race/ethnicity, age, and insurance status. Data from 2007 to 2016 were obtained, and breast cancer stage trends were assessed. Additionally, preexpansion years (2012-2013) were compared with postexpansion years (2015-2016) to assess Medicaid expansion in 2014. Data were analyzed from August 12, 2019, to January 19, 2020. The cohort included a total of 1 796 902 patients with primary breast cancer who had private insurance, Medicare, or Medicaid or were uninsured across 45 states. Main Outcomes and Measures: Percent change of uninsured patients with breast cancer and stage at diagnosis, stratified by insurance status, race/ethnicity, age, and state. Results: This study included a total of 1 796 902 women. Between 2012 and 2016, 71 235 (4.0%) were uninsured or had Medicaid. Among all races/ethnicities, in expansion states, there was a reduction in uninsured patients from 22.6% (4771 of 21 127) to 13.5% (2999 of 22 150) (P < .001), and in nonexpansion states, there was a reduction from 36.5% (5431 of 14 870) to 35.6% (4663 of 13 088) (P = .12). Across all races, there was a reduction in advanced-stage disease from 21.8% (4603 of 21 127) to 19.3% (4280 of 22 150) (P < .001) in expansion states compared with 24.2% (3604 of 14 870) to 23.5% (3072 of 13 088) (P = .14) in nonexpansion states. In African American patients, incidence of advanced disease decreased from 24.6% (1017 of 4136) to 21.6% (920 of 4259) (P < .001) in expansion states and remained at approximately 27% (27.4% [1220 of 4453] to 27.5% [1078 of 3924]; P = .94) in nonexpansion states. Further analysis suggested that the improvement was associated with a reduction in stage 3 diagnoses. Conclusions and Relevance: In this cohort study, expansion of Medicaid was associated with a reduced number of uninsured patients and a reduced incidence of advanced-stage breast cancer. African American patients and patients younger than 50 years experienced particular benefit. These data suggest that increasing access to health care resources may alter the distribution of breast cancer stage at diagnosis.