Racial differences in genomic testing and receipt of endocrine therapy in early-stage breast cancer

Genomic testing in early-stage hormone-positive breast cancer is the standard of care. However, decisions based on genomic testing results are predicated on the assumption that patients receive endocrine treatment. We sought to investigate racial differences in genomic testing and adjuvant treatment in breast cancer.

A retrospective, population-based hospital registry study using the National Cancer Database. Participants included women with stages I-II, ER + breast cancer between 2010 and 2014. Sociodemographic factors were analyzed. Primary outcomes were the utilization of genomic testing and receipt of endocrine therapy. Logistic regression modeling was used to compute crude and adjusted odds of genomic testing and receipt of endocrine therapy.

Among a total sample size of 387,008 patients, 147,863 (38.2%) underwent genomic testing. Older age (≥ 70 years) was associated with a lower adjusted odd of genomic testing (OR 0.33; 95% CI 0.32-0.34, p =  < 0.0001). Black patients had lower odds of receiving genomic testing on multivariate analysis compared to Whites (OR 0.82; 95% CI 0.80-0.85, p =  < 0.0001). In patients who underwent a genomic test, compared to Whites, Blacks had a lower odds of receiving endocrine therapy (OR 0.86; 95% CI 0.80-0.93, p =  < 0.0001) even if they did not receive adjuvant chemotherapy (OR 0.90; 95% CI 0.82-0.98, p = 0.014).

In a national sample of breast cancer patients, Black women are less likely to get genomic testing and receive hormonal therapy, even when adjuvant chemotherapy is omitted. A priority in addressing breast cancer disparities is to ensure adherence to hormonal therapy among all women, including those who do not receive adjuvant chemotherapy.