New research showing genetic differences in breast cells suggests standard treatments for breast cancer are less effective for Black women, who disproportionately suffer and die from the disease.
The study from the Sanford Burnham Prebys Medical Discovery Institute highlights the need to include more Black people in trials, experts said. More inclusive data is essential to help fill knowledge gaps and improve treatment plans.
We really need to take that on board and say, ‘Are we doing the best job we can in implementing precision medicine for everyone? Or have we been using a one-size-fits-all approach for a little too long?’” said lead author and cancer researcher Svasti Haricharan.
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Black women have the highest breast cancer death rates of any racial group – 40% higher than white women and more than double Asian and Pacific Islander women, who have the lowest death rates, according to the American Cancer Society. Often diagnosed at younger ages than white women, Black women under 50 die at double the rate of white women. More than a fifth of breast cancers in Black women are triple negative, the most aggressive form.
For the study, researchers looked at cells of women with the most common breast cancer subtype, estrogen receptor positive (ER+), which is less aggressive and more treatable.
The researchers found genes that repair DNA damage signal differently in Black women’s breast cells compared with white women’s cells. Eight specific genes behind DNA repair were expressed differently in Black women, as well as other markers that influence how fast cells grow.
These differences were associated with lower survival rates and could make ER+ cancer in Black women less responsive to the standard treatment plans that work well in white women – on whom the treatments were mostly tested, according to the authors of the study published last week in Therapeutic Advances in Medical Oncology. The findings suggest Black women with this type of breast cancer could benefit from earlier treatment with CDK inhibitors, a type of drug that helps stop cancer cells from multiplying.
“When Black women get this extremely treatable, curable form of breast cancer, they actually have much worse outcomes than white women who get this disease,” Haricharan said. “We should be doing things differently in the clinic. … (Black women are) getting worse quality of treatment than white women, just because we don’t understand what’s happening in those breast cancer cells as well as we understand what’s happening in breast cancer cells in white women.”
Increasing the representation of Black women in breast cancer clinical trials – which mostly consist of white women – would help. Black people are underrepresented in cancer clinical trials, making up just 7% of enrollment.
“There’s underrepresentation in these data sets that then are used for treatment recommendations,” said Vivian Bea, a breast cancer specialist surgeon at Weill Cornell Medicine in New York City.
“In order for precision medicine to really be equitable, to really transcend or not just be applicable to one race or ethnicity, we really have to put our heads together and find ways in which we can increase clinical trial enrollment,” Bea said.
Black women’s disparities in deaths and responses to treatments are a reflection of historical exclusion and racism, Bea said. Landmark trials that changed the face of how breast cancer is treated lacked Black women, she noted. The study highlights differences that get overlooked because of a lack of diversity in clinical trials that define treatment.
“Clinical trials matter,” she said. “You have to have representation in order to make these treatment recommendations for precision medicine to work.”
It’s why she and her team developed a process to educate and empower patients to understand the importance of trials and take part.
“The cause of higher mortality in Black women is multifactorial,” she said. “We have to continue to put these pieces of the puzzle together to determine why that disparity exists so that we can then combat it. This is one small piece of the puzzle that is highlighting that molecular factors may be contributory.”
Nikhil Wagle, a medical oncologist and cancer researcher at Dana-Farber Cancer Institute and the Broad Institute, commended the study and said he’s looking forward to follow-up research.
“This study is a great first step,” he said. “And now more work needs to be done in larger data sets to validate these findings and continue to make more discoveries like this, so that we have equitable precision medicine.”
Wagle said a lack of Black representation in treatment studies and data is “a huge problem” within the field. He leads an effort to create a large, diverse cancer data set as director of Count Me In, a nonprofit that allows patients to share medical information, experiences and samples to propel research.
“It sets up a lot of questions that need to be asked and need to be further validated in larger data sets and with more rigorous prospective trials,” Wagle said about the study. “Precision medicine is only as precise as the underlying information that went into making those decisions. And so the disparities exist: both the disparities in cancer care but also the disparities in cancer research. And both of those things need to be corrected.”