Sociodemographic disparities in molecular testing for breast cancer

Abstract

Purpose: Molecular testing is a critical component of breast cancer care used to identify the presence of estrogen and/or progesterone receptors (jointly hormone receptors—HRs) and the expression of human epidermal growth factor 2 (HER2) on a tumor. Our objective was to characterize trends and predictors of lack of molecular testing among female breast cancer patients overall and by sociodemographic characteristics. Methods: We examined data on female breast cancer patients diagnosed between 2010 and 2016 from Surveillance Epidemiology and End Results-18. Joinpoint regression analyses assessed annual percent change (APC) in lack of ER, PR, or HER2 testing. Multivariable, multilevel logistic regression models identified factors associated with lack of molecular testing. Results: A nominally lower proportion of rural patients did not receive molecular testing (e.g., 1.8% in rural vs. 2.3% in urban for HER2). For all tests, a higher proportion of Hispanic and non-Hispanic Black women were not tested. Across all characteristics, improvement in testing was noted, although disparities among groups remained. For example, lack of HER2 testing improved from 3.2 to 1.7% in White patients (APC = − 10.05) but was consistently higher in Black patients 3.9 to 2.3% (APC = − 8.21). Multivariable, multilevel models showed that older, non-Hispanic Black, and unpartnered women were at greater odds of not receiving molecular testing. Conclusions: While lack of molecular testing of breast cancer patients is relatively rare, racial/ethnic, insurance status, and age-related disparities have been identified. To reduce testing and downstream treatment and outcome disparities, it is imperative for all breast cancer patients to receive molecular testing.