The risk of developing breast cancer is similar between white and black women, but black women are 42 percent more likely to die from aggressive subtypes of the disease, according to a study.
A different distribution of genetic mutations may be the reason for the disparity, researchers said.
They said the findings could lead to an improvement in cancer risk assessment for black women and encourage the development of personalized therapies to fight aggressive subtypes of breast cancer.
The study, “Comparison Of Breast Cancer Molecular Features And Survival By African And European Ancestry In The Cancer Genome Atlas,” was published in the journal JAMA Oncology.
Researchers looked at the records of 930 breast cancer patients, 776 of them white women with a mean age at diagnosis of 59.5 years and 154 of them black women with a mean age at diagnosis of 55.6 years. The team compared breast cancer-free interval, tumor features, and genetic mutations between the groups.
Black women had a shorter breast cancer-free interval and carried more mutations in their DNA. Black women with hormone receptor positive, HER2-negative breast cancer also were at greater risk of the disease recurring than white women, researchers said.
In addition, black women were more likely to be diagnosed at a younger age and develop aggressive breast-cancer subtypes, such as basal-like or triple-negative cancers. The tumors in these subtypes lack estrogen receptors, progesterone receptors and HER2, a gene that often plays a role in breast cancer.
Another finding was that genes expressed several molecules differently in black women than in white. This supports the notion that genetics play a role in black women developing an aggressive breast cancer subtype and dying of it. Expression is the process by which information from a gene is used to create a functional product, like a protein.
“People have long associated breast cancer mortality in black women with poverty, or stress, or lack of access to care, but our results show that much of the increased risk for black women can be attributed to tumor biological differences, which are probably genetically determined,” Dr. Olufunmilayo Olopade, the study’s senior author, said in a news release.
“The good news,” she said, “is that as we learn more about these genetic variations, we can combine that information with clinical data to stratify risk and better predict recurrences — especially for highly treatable cancers — and develop interventions to improve treatment outcomes.”
Olopade said the findings are “a step toward the development of polygenic biomarkers, tools that can help us better understand each patient’s prognosis and, as we learn more, play a role in choosing the best treatment.”
“Genes matter,” she said. “This is a foot in the door for precision medicine, for scientifically targeted treatment.”
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