Impacts of Medicaid Expansion on Stage at Cancer Diagnosis by Patient Insurance Type

Abstract

Introduction: The expansion of Medicaid under the Affordable Care Act increased access to health care for millions of low-income Americans. However, the longer-term impacts of the policy on cancer outcomes remain unknown. This study examined the impact of Medicaid expansion on early- and late-stage diagnosis for 4 common cancers (breast, cervical, colorectal, and lung) using 4 full years of postpolicy data.

Methods: Patients aged 40-64 years diagnosed with breast, cervical, colorectal, or lung cancer from 2010 to 2017 were identified using the National Cancer Database. Difference-in-difference analyses compared changes in early-stage and late-stage diagnoses among expansion states with those among nonexpansion states. Subgroup analyses explored potential effect modification by insurance type. Data analysis was performed from June to October 2021.

Results: The proportion of early stage diagnosis of breast (difference in difference=1.58, 95% CI=0.89, 2.27), cervical (difference in difference=3.20; 95% CI=0.44, 5.95), colorectal (difference in difference=1.98; 95% CI=1.18, 2.78), and lung (difference in difference=1.74; 95% CI=0.98, 2.50) cancers increased more in expansion states than in nonexpansion states, whereas late-stage diagnosis of colorectal (difference in difference= -2.12; 95% CI= -2.98, -1.27) and lung (difference in difference= -1.87; 95% CI= -2.89, -0.84) cancers decreased more in expansion states following implementation of the Affordable Care Act. In subgroup analyses, difference-in-difference estimates for all sites and stages (except late-stage cervical cancer) were significant and larger in magnitude among Medicaid-insured than among privately insured patients.

Conclusions: Study results highlight the positive impacts of Medicaid expansion on earlier diagnosis of several cancers for which screening and early detection exist, and subgroup analyses revealed greater positive effects among Medicaid-insured patients most targeted by the policy.