Black women are more likely to develop aggressive forms of breast cancer than white women because of genetic differences in the tumours, a new study suggests.
The finding that genetic characteristics of more aggressive tumours may be more prevalent among black women could help explain racial differences in survival rates. The researchers said their findings could help scientists develop more targeted treatments for the disease.
Read: Risk factors for breast cancer
Previous studies have already found that, compared with white women, black women have a higher prevalence of breast cancers that do not respond to hormone therapy so-called "triple-negative" breast cancers.
Now, the new study reports that black breast cancer patients also have a "significantly higher prevalence of the TP53 driver mutation, basal tumour subtype and greater genomic diversity within tumours, all of which suggest more aggressive tumour biology," the study's lead author, Dr Tanya Keenan, of Massachusetts General Hospital Cancer Centre in Boston, said in a hospital news release.
"The higher risk of tumour recurrence that we observed among African American women was reduced when controlling for those factors, suggesting that these genomic differences contribute, at least partly, to the known racial disparity in the survival of African American and Caucasian breast cancer patients," Keenan added.
Read: More black women die of breast cancer
Advancements in the diagnosis and treatment of breast cancer have reduced the overall death rate of the disease, but this positive trend is less apparent among black women, the researchers pointed out.
Black women with breast cancer in the United States are 40 percent more likely to die from their disease than white women, a disparity that can't be explained solely by social and economic factors, such as income, insurance and access to care, the study authors said in the news release.
More aggressive tumours
For the study, the investigators analysed genetic differences between the tumours of 105 black women and 664 white women diagnosed with cancer between 1988 and 2013, to determine how genes could influence cancer recurrence.
The same five tumour-specific mutations were most prevalent among all of the women included in the study, but more black women had tumours driven by TP53 mutation. Women with this mutation were more likely to suffer a recurrence and their relapse also occurred more quickly, according to the study, which was published online in the Journal of Clinical Oncology.
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Meanwhile, white women more often had tumours with the PIK3CA mutation. Overall, however, black women had more mutations within each tumour and greater prevalence of mutations associated with more aggressive tumours, the findings showed.
"Our study adds important pieces to the puzzle of why African American women with breast cancer are less likely to survive," said the study's senior author, Aditya Bardia, an assistant professor of medicine at Harvard Medical School and attending physician at the Massachusetts General Hospital Cancer Centre.
"If our findings are confirmed by additional studies, they may open doors to the development of targeted therapies against the tumour subtypes more likely to affect African Americans, and potentially help reduce racial disparities in breast cancer," Bardia explained in the news release.
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