Medicaid expansion and thyroid cancer stage at presentation: A comparative study of two US states.

BACKGROUND

The Affordable Care Act (ACA) enabled states to expand Medicaid eligibility, extending coverage to millions, particularly in California. While Medicaid expansion has been linked to earlier diagnoses in several cancers, its impact on thyroid cancer-a slow-growing malignancy lacking formal screening-remains unclear.

OBJECTIVE

To assess whether Medicaid expansion influenced thyroid cancer stage at presentation.

METHODS

A retrospective cohort study using SEER data (2009-2020) compared adults aged 18-64 diagnosed with thyroid cancer in California (expansion) and Texas (non-expansion). Difference-in-differences logistic regression evaluated stage changes pre- (2009-2013) and post- (2016-2020) expansion, excluding a 2014-2015 washout period.

RESULTS

Among 63,073 patients, no significant difference in stage at diagnosis was observed between states. Estimates for localized, regional, and distant disease changes ranged from -1.3 ​% to 1.1 ​% (all 95 ​% CIs included zero).

CONCLUSION

Medicaid expansion was not associated with a significant shift in thyroid cancer stage at presentation.