NEW YORK (GenomeWeb) – Race and socioeconomics appear to be key factors in both the use of genomic testing and how the test results guide physicians' treatment decisions in early-stage breast cancer patients, according to a new study published this week.
By examining more than 140,000 patient records, researchers from the University of Colorado, Aurora, found that African-American patients, Medicaid and Medicare patients, and those treated at community centers were significantly less likely to be tested with Genomic Health's Oncotype DX assay, which uses the expression of 21 genes to predict chemotherapy benefit and breast cancer recurrence.
Additionally, the team discovered that younger African-Americans who received testing were more likely than other groups to receive chemotherapy even when their test scores recommended against such treatment.
"We meant this study as a kind of state of the union for the use of this test," lead author Jagar Jasem said in a statement. "What we found were some pretty stark disparities along socioeconomic and racial lines."
As they reported in the Journal of Clinical Oncology this week, Jasem and his colleagues analyzed data in the National Cancer Database from 143,023 patients diagnosed with early breast cancer between 2004 and 2012. They used multivariate logistic regression analysis to estimate the covariates associated with use of the test and its impact on chemotherapy decisions.
The investigators found that the recurrence score (RS) assay was ordered for 54 percent of the patients, and that its use was significantly associated with patients who were young, white, receiving care at academic centers, privately insured, and had grade 2 or grade 3 disease.
While African-Americans were less likely to receive testing with Oncotype DX, those who did were more likely to be tested even when they did not meet the National Comprehensive Cancer Network recommendations for such testing. Factors also contributing to the likelihood of RS testing included treatment at community facilities, higher tumor grade, and being male. "Slightly higher odds were also observed for beneficiaries of governmental health insurance compared with those who have private health insurance," the authors wrote in their paper.
Additionally, the UC Aurora group found that younger black patients and patients at community facilities were more likely to receive chemotherapy even if they had low assay scores. Patients with private insurance were also more likely to receive chemotherapy than those on government assistance.
"We show that doctors are absolutely using this test to decide who gets chemotherapy along with their treatment," Jasem said in the statement. "In fact, of all the variables we explored, this test was most strongly associated with the chance that a patient goes on to receive chemotherapy. But what we show is that the treatment of minority and low socioeconomic patients is more likely to be disconnected from these test results."
The researchers caution, however, that their study does have certain limitations, including its lack of data on patients tested after 2012. "Factors associated with the use and overuse of the test may be different after 2012 owing to a presumably wider availability, better accessibility, and higher adoption rates of the test by oncologists," they wrote.