The Oncotype DX test, which helps guide treatment decisions for women with early-stage breast cancer, may be less accurate for Black women than for non-Hispanic White women, a new study suggests, according to the National Cancer Institute.
The test measures how aggressive a woman’s breast cancer is and helps her and her doctor decide if she should get chemotherapy after surgery. Oncotype DX works by looking at the activity of a group of genes in the tumor and calculating a score between 0 and 100. The score predicts the risk of the cancer coming back, which can help gauge the patient's risk of dying from breast cancer.
The new study showed that, overall, Black women had higher Oncotype DX scores than White women. And among women with similar scores, Blacks were more likely than Whites to die of breast cancer. The researchers also determined that the test was not as good at predicting the risk of breast cancer death for Black women, according to the results published earlier this year in JAMA Oncology.
These findings “raise the question of whether the test is less accurate [at] identifying which [Black] patients need chemotherapy,” noted the study’s leader, Kent Hoskins, MD, Associate Professor of Medicine the University of Illinois at Chicago.
Hoskins and his colleagues are currently exploring that question. But until then, current medical practices for recommending chemotherapy based on Oncotype DX scores shouldn’t change, he said.
“The larger message here,” Hoskins stressed, “is that as we develop new tests like this, it’s really important that the study populations have greater racial diversity because there really can be differences that influence the performance of these tests.”
The Oncotype DX test is widely used to guide treatment decisions for people with a type of early-stage breast cancer, known as ER positive or hormone receptor positive.
But relatively few Black women participated in the studies that were done to develop and validate the test, Hoskins explained. That made the researchers wonder how well the test actually performs in Black women, he said.
The team looked at data from a specialized database developed by NCI’s Surveillance, Epidemiology, and End Results (SEER) Program. The database includes information on more than 86,000 breast cancer patients from across the country who had Oncotype DX test results available. About 74% were White, 8% were Black, and 9% were Hispanic. All of the women had early-stage ER-positive breast cancer.
Black women were more likely than non-Hispanic White women to have a high score (greater than 25) on the Oncotype DX test, the scientists found. But even after taking into account age, tumor size, and whether there was cancer in the lymph nodes — factors that are linked with more aggressive breast cancer — Black women were still more likely to have a higher Oncotype DX score.
Oncotype DX scores are grouped into three categories that reflect a patient’s risk of their cancer returning. Scores under 10 indicate a low risk, while those between 11 and 25 are intermediate risk, and scores 26 and above are considered high risk.
Most patients with low and intermediate risk scores get hormone therapy after surgery, whereas those with high scores get chemotherapy in addition to hormone therapy.
Within all three risk groups, Black women were more likely than Whites to die of breast cancer during the follow-up period (a median of 4.5 years), the research team found. This pattern was seen only in women with breast cancer that hadn’t spread to the lymph nodes (what’s known as node-negative breast cancer).
These results partially confirm preliminary findings from the TAILORx trial, a clinical study of more than 10,000 women who received breast cancer treatment based on Oncotype DX test results.
Hoskins and his colleagues also calculated how well Oncotype DX predicts the prognosis — specifically the risk of breast cancer death — for women with node-negative breast cancer in each racial/ethnic group. They found that the test had a lower accuracy for Black women than White women, meaning it was not as accurate at predicting death from breast cancer.
This finding suggests that the test may need to be “recalibrated” for Black patients, Hoskins explained. It’s possible that further studies may find that there “should be different cut points for recommending chemotherapy in racial/ethnic minority women,” he said.