In a simple definition, cancer is a disease of the cells, which is caused by gene mutations. For a proportion of patients, including women with hormone receptor positive (HR+) breast cancer, gene expression profiling has a substantial impact on treatment decision-making by determining which patients might—or might not—respond to particular treatment options.
Gene expression profiling tests are readily available, yet researchers recently found that white women with breast cancer are far more likely to receive a particular test—Oncotype Dx™ (ODx)—than black or Hispanic women with the same diagnosis. The study, "Racial and Ethnic Disparities in Oncotype Dx™ Test Receipt in a State-Wide Population-Based Study," led by Cary P. Gross, MD, Yale University School of Medicine and a member of Yale Cancer Center, is published in the March issue of JNCCN - Journal of the National Comprehensive Cancer Network.
"Observed racial and ethnic disparities in Oncotype DX testing are particularly concerning given its potential to guide treatment decisions for women with early stage breast cancer. Unequal access to genetic testing has the potential to further exacerbate disparities in treatment quality, survival, and quality of life," said Dr. Gross.
Testing Within vs. Outside of the Guidelines
According to lead author Brigette Davis, MPH, the study built on existing research in two ways: identifying racial disparities in a state-wide, population-based analysis; and identifying the use of ODx among women for whom the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®) recommend it, as well as among women for whom NCCN Guidelines® did not recommend testing. This distinction is important, Ms. Davis says, "because evidence-based guidelines are intended to remove subjectivity from clinical decision-making; utilization outside of these guidelines further highlights how nonclinical factors may impact outcomes and costs for patients and payers."
The team looked at a cohort of more than 8,000 women across the state of Connecticut who were diagnosed with HR+ breast cancer between 2011 and 2013. Among those women, Dr. Gross and colleagues performed a retrospective analysis of race, ethnicity, and ODx receipt, dividing the population among those who did and did not qualify for ODx testing according to the NCCN Guidelines for Breast Cancer.
Among the population, more than 80% of the patients were white, 6.3% were black, and 7.4% were Hispanic. Researchers found that for the NCCN Guidelines-recommended group, white patients were more likely to receive ODx testing than black and Hispanic women: 51.4% vs. 44.6% and 47.7%. Even after further adjusting for tumor and clinical characteristics, researchers observed significantly lower ODx use among black and Hispanic women compared with white women in the recommended group. Significant testing variation between the white, black, and Hispanic patients were also noted in the non-Guidelines-recommended group: 21.2% vs. 9.0% and 9.7%, respectively.
"Understanding and mitigating racial barriers to gene expression testing in women with breast cancer is imperative to narrowing disparities in breast cancer outcomes," said Dr. Gross. "Our study reinforces the notion that at the same time the scientific community is discovering exciting new ways to help prevent or treat breast cancer, our broader community of clinicians and policy makers must ensure that these breakthroughs are accessible for all patients who need them, regardless of the color of their skin, their nation of origin, or the size of their bank account."
Overuse of Oncotype DX Testing
In addition to racial disparities, the study uncovered significant use of ODx outside NCCN Guidelines recommendations—confirming earlier concern about overuse of genetic profiling in patients with breast cancer. As outlined in the study, between 2011 and 2013, the NCCN Guidelines for Breast Cancer did not recommend ODx for patients with higher-risk disease, yet more than 18%—or 1,100 women—received ODx testing.
Amy E. Cyr, MD, of Siteman Cancer Center at Barnes-Jewish Hospital and Washington University School of Medicine and a member of the NCCN Guidelines Panel for Breast Cancer noted, "Papers like this are important to make us aware of our practice patterns; I expect that most physicians do not perceive that they use these tests differently when caring for minority women. Stricter adherence to treatment guidelines should reduce such racial disparity. We cannot address disparity in outcomes without addressing disparity in treatment patterns."
"Reports such as this Yale study of racial and ethnic disparities regarding Oncotype testing are important for the medical community to receive and digest," said Benjamin O. Anderson, MD, of Fred Hutchinson Cancer Research Center/Seattle Cancer Care Alliance and Vice-Chair of the NCCN Guidelines Panel for Breast Cancer. "Patients who have a complete understanding—without fear—of their treatment options, are more likely to seek and receive the care they need. As clinicians who educate each patient about their care, the solution is very much in our hands."