A test commonly used to predict the aggressiveness of early stage estrogen receptor (ER)-positive breast cancer is significantly less likely to be used for African American patients, Medicare and Medicaid recipients, and patients treated at community facilities, a study published online ahead of print in the Journal of Clinical Oncology has shown.1

“We meant this study as a kind of state of the union for the use of this test. What we found were some pretty stark disparities along socioeconomic and racial lines,” says Jagar Jasem, MD, MPH, investigator at the University of Colorado (CU) Cancer Center and the study’s lead author.2

Use of the 21-Gene Recurrence Score Assay, also known as the Oncotype DX test, was analyzed in this study. The assay determines the status of 21 genes known to predict the aggressiveness of early-stage, ER-positive breast cancer; specifically, the likelihood of disease recurrence after surgery and hormonal therapy, and thus the potential benefit of adjuvant chemotherapy for an individual patient with breast cancer.

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Tests results are presented as a score on a scale of 1 to 100: a score of less than 18 implies the side effects of chemotherapy outweigh the benefit to the patient, 18 to 30 implies adjuvant chemotherapy could benefit the patient, and 31 or higher implies a high risk for recurrence, therefore, adjuvant chemotherapy would be beneficial for the patient.

For the study, the researchers reviewed 143 032 patient records. They found that the 21-gene assay is significantly less likely to be used in managing the treatment of African American patients. Medicaid and Medicare recipients and patients treated at community centers were also less likely to be tested.

Test scores for those African American patients who were tested were higher, indicating aggressive disease and benefit from chemotherapy. In addition to undertesting in this population, younger African American patients received chemotherapy despite a low score on the assay results.

“This is the first study that provides an analysis of the current trends and differences in the use of this assay and its impact on recommendations for chemotherapy,” Jasem says. “And from this population-based analysis, we can see significant differences in the use and clinical implications of the test on the basis of race, insurance, and type of facility.”


1. Jasem J, Amini A, Rabinovitch R, et al. 21-Gene recurrence score assay as a predictor of adjuvant chemotherapy administration for early-stage breast cancer: an analysis of use, therapeutic implications, and disparity profile [published online ahead of print March 21, 2016]. J Clin Oncol. doi:10.1200/JCO.2015.65.0087.

2. Racial, socioeconomic disparities in genomic test used in early-stage breast cancer [news release]. EurekAlert! Web site. http://www.eurekalert.org/pub_releases/2016-03/uoca-rsd031916.php. Published March 21, 2016. Accessed April 1, 2016.