Progress Made In Identifying Black's Breast Cancer Risks

ORLANDO  — A woman's ethnicity as well as her genetic makeup are two of the main risk factors for hereditary breast cancer.

Research into understanding and treating hereditary breast cancer was presented today at the Era of Hope conference, a scientific meeting hosted by the Department of Defense Breast Cancer Research Program (BCRP).

About 5 to 10 percent of breast cancers are thought to be hereditary, resulting from defective genes inherited from a parent. The most common cause of hereditary breast cancer is an inherited mutation in the BRCA1 or BRCA2 gene; the risk may be as high as 85 percent for members of some families with these mutations.1 And while White women are more likely to develop breast cancer, African American women are more likely to die from the disease, partly because African Americans have more aggressive tumors.

Studies presented at Era of Hope explore the genes that contribute to breast cancer risk in African Americans, and the possibility that vitamin D intake might help mitigate it in this population.

Other studies look at how daughters of women with BRCA 1 or BRCA2 mutations manage their own risk of breast cancer, and how the identification of a particular gene might lead to treatment for the very deadly triple-negative breast cancer.

"Some women are born with a greater risk of developing more aggressive forms of breast cancer," said Captain Melissa Kaime, M.D., Director of the Congressionally Directed Medical Research Programs (CDMRP), under which the BCRP is managed. "Research presented at the Era of Hope provides new insights into the specific gene mutations that lead to this risk, enabling us to develop targeted treatments and to better assist those women to manage their inherited predisposition to the disease."

Toward Understanding Genetic Susceptibility for Breast Cancer in Women of African Ancestry
Principal Investigator: Christopher Haiman, ScD, University of Southern California

Studies of genetic links to breast cancer have been conducted almost exclusively in populations of European ancestry and have firmly established a number of gene locations that are associated with breast cancer susceptibility. While these discoveries provide support for the theory that many genes can predispose someone to cancer,2 and provide clues to important biological pathways involved in the development of cancer, the degree to which these genetic associations can be generalized broadly to other racial/ethnic populations is unclear. A genome-wide association study among women of African ancestry was initiated to identify additional genetic risk factors for breast cancer in this population.

As a first step, this study examined genetic variation at all 18 genetic regions previously associated with breast cancer risk to both improve the current set of risk markers in African Americans and to identify new variants that may be associated with risk. Through fine-mapping, markers were identified that better define the association in African Americans in seven regions. Among them, three showed evidence of independent signals. All together, these risk markers allow for an improved ability to predict the risk of breast cancer development for African Americans over previously-reported markers.

"We are encouraged by these findings, as we continue to learn more about genetic susceptibility to breast cancer in African American women," said Dr. Christopher Haiman of the University of Southern California. "We look forward further research aimed at identifying risk variants for breast cancer in this population, in particular those for estrogen receptor negative disease which has a greater incidence among women of African ancestry. We are also working to further develop and validate this risk model to improve breast cancer risk prediction in this population using risk variants."