A common test used to determine whether breast cancer patients should receive chemotherapy may make bad recommendations for some black women, leading them to forego chemotherapy when it could help them, according to new research from the University of Illinois at Chicago.
The test, known as the 21-gene breast recurrence score, is the most commonly ordered biomarker test used to guide doctors’ recommendations for patients with estrogen receptor-positive breast cancer -; The most common form of cancer. The test helps identify which tumors are likely to be the most aggressive and thus better candidates for chemotherapy.
The researchers conducted a statistical analysis on a database that included both test results and death records of more than 70,000 women with early-stage estrogen receptor-positive breast cancer. They found that the trial may have underestimated the benefits of chemotherapy for black women by suggesting that some, particularly younger patients, are less likely to benefit from chemotherapy, when in fact they may benefit.
“The test can be the wrong treatment,” explains Dr. Kent Hoskins, professor of oncology at UIC and senior author Journal of the National Comprehensive Cancer Network study.
The researchers conducted an exploratory analysis to gauge whether the test’s cutoff point for recommending chemotherapy for black women should be lowered, and it should be. But Hoskins says a fuller study needs to be done before recommendations can be made.
Still, “research shows that it may be inappropriate for doctors to use exact cutoffs and tests regardless of race or ethnicity because there are underlying differences in biology,” said Hoskins, who is also a member of the University of Illinois Cancer Center.
Almost all patients with this type of cancer receive pills that block estrogen, whether they receive chemotherapy or not. Researchers suspect that this treatment gap is because tumors in black women are less likely to respond to estrogen-blocking pills than tumors in other women. So chemotherapy helps improve outcomes for them more than it does for women who benefit from pills alone, Hoskins said. The researchers have another paper at work looking at this question.
The paper is part of work by UIC researchers looking at outcomes for black women with estrogen receptor-positive tumors. While much attention has been focused on the negative outcomes for black women who have difficult-to-treat triple-negative breast cancer, which accounts for about 20% of breast cancers for black women, Hoskins explained. Previous studies by this group have shown that black women are more likely than white women to develop triple-negative breast cancer, but they are not more likely to die from it. Yet they are more likely to die from the more common estrogen receptor-positive form.
Hoskins emphasized that while this new paper points to biological differences in tumors for black versus white women, it does not rule out the contribution of a host of social factors caused by structural racism. But those factors, like access to health care, don’t account for the whole picture. In fact, Hoskins believes that the same social determinants of health that lead to poor outcomes for black women in the health care system also cause biological differences in tumors. The researchers have a paper working on this question as well.
We believe that it is actually the same forces that lead to disparities in care that are driving these more aggressive biologics.”
Dr. Kent Hoskins, professor of oncology at UIC
Other UIC authors of the paper are Hsiao-Ching Huang, Drs. VK Gadi, Dr. Ona Danciu, and Garth Rauscher, from the Cancer Center, College of Pharmacy, College of Medicine, and School of Public Health.