Racial disparities in omission of oncotype DX but no racial disparities in chemotherapy receipt following completed oncotype DX test results.

PURPOSE: To examine racial/ethnic disparities in Oncotype DX (ODX) testing among patients with node-negative, estrogen receptor (ER)-positive, human epidermal growth factor receptor 2 (HER2)-negative breast cancers and possible racial/ethnic disparities in chemotherapy receipt following ODX testing within Recurrence Score (RS) category (Not Done, Low, Intermediate, High), as well as chemotherapy receipt time trends within RS categories.
METHODS: A retrospective cohort list of 125,288 women who were potentially indicated for ODX testing from 2010 to 2014 was obtained using the National Cancer Database. We fit multivariate logistic regression predicting chemotherapy receipt, adjusting for clinical factors, patient demographic factors, and hospital-level factors, separately by RS category, and calculated odds ratios (OR) and 95% confidence intervals (CI), as well as time trends.
RESULTS: Overall, ODX testing was completed for 46.1% of Non-Hispanic (NH) Whites, 43.9% of NH Blacks, and 41.7% of Hispanics. Among patients who did not receive ODX testing, NH Black and Hispanic women both experienced statistically significant increases in chemotherapy receipt relative to NH White women (NH Black OR 1.23; 95% CI 1.11-1.37; Hispanic OR 1.23; 95% CI 1.07-1.42). However, among patients with ODX results, no statistically significant racial/ethnic differences in chemotherapy receipt were observed within strata of RS category. Trend analyses demonstrated increasing adherence to national guidelines for ODX testing.
CONCLUSIONS: We identified racial disparities in omission of ODX testing but no differences in chemotherapy receipt if ODX test results were obtained, suggesting increasing access to ODX testing may improve racial equality in efficacious use of adjuvant chemotherapy for ER-positive HER2-negative breast cancer.