Changes in initiation of adjuvant endocrine therapy for breast cancer after state health reform

BACKGROUND: Socioeconomic differences in receipt of adjuvant treatment contribute to persistent disparities in breast cancer (BCA) outcomes, including survival. Adjuvant endocrine therapy (AET) substantially reduces recurrence risk and is recommended by clinical guidelines for nearly all women with hormone receptor-positive non-metastatic BCA. However, AET use among uninsured or underinsured populations has been understudied. The health reform implemented by the US state of Massachusetts in 2006 expanded health insurance coverage and increased the scope of benefits for many with coverage. This study examines changes in the initiation of AET among BCA patients in Massachusetts after the health reform. METHODS: We used Massachusetts Cancer Registry data from 2004 to 2013 for a sample of estrogen receptor (ER)-positive BCA surgical patients aged 20–64 years. We estimated multivariable regression models to assess differential changes in the likelihood initiating AET after Massachusetts health reform by area-level income, comparing women from lower- and higher-income ZIP codes in Massachusetts. RESULTS: There was a 5-percentage point (p-value< 0.001) relative increase in the likelihood of initiating AET among BCA patients aged 20–64 years in low-income areas, compared to higher-income areas, after the reform. The increase was more pronounced among younger patients aged 20–49 years (7.1-percentage point increase). CONCLUSIONS: The expansion of health insurance in Massachusetts was associated with a significant relative increase in the likelihood of AET initiation among women in low-income areas compared with those in high-income areas. Our results suggest that expansions of health insurance coverage and improved access to care can increase the number of eligible patients initiating AET and may ameliorate socioeconomic disparities in BCA outcomes. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12885-021-08149-0.