Racial Differences in Triple Negative Breast Tumors Among Women in Atlanta
Behind the Cancer Headlines®
April 10, 2006
They're commonly referred to as "triple negatives" – breast cancers characterized by three biological components that make the disease more difficult to treat. Oncologists base treatment decisions on the presence of three hormones known to fuel most breast cancers – estrogen receptors, progesterone receptors and human epidermal growth factor receptor 2, or HER2. The most effective chemotherapy agents for breast cancer, such as tamoxifen and trastuzumab (Herceptin), work by targeting these hormones. Women with triple negative tumors lack all three.
In a study of racial differences in the prevalence of triple negative invasive breast tumors, a team of researchers from Emory University in Atlanta, the Fred Hutchinson Cancer Research Center in Seattle, and the Centers for Disease Control, found the incidence of triple negative disease in African-American women to be more than twice that of white women.
"Triple negative disease has not been adequately described or studied, particularly among minority populations," said Emory researcher Mary Jo Lund, Ph.D. "It has the worst prognosis because the tumors have the worst characteristics and preclude the use of the most common, effective treatments," said Lund.
To assess the racial differences in the prevalence of triple negative breast cancer, Lund and her colleagues in Atlanta analyzed tumor data from Fred Hutchinson Cancer Research Center collaborator Peggy Porter, M.D., and data from their study of racial differences in progression of breast cancer among Atlanta women under the age of 55.
When the data was broken down by race and adjusted for age and stage of disease at the time of diagnosis, the team found that 47 percent of tumors in black women were negative for estrogen receptor, progesterone receptor, and HER2, compared to 22 percent in whites.
There also were strong associations found in African-American women and white women between triple negative disease and high-grade tumors and abnormal expression of p53, a tumor-suppressor gene with cancer-inhibiting properties.
At all ages, African-American women are at lower risk for breast cancer compared to white women. However, for women under the age of 50, African-American women are at increased risk over white women of the same age. "There is also evidence that younger African American women have breast tumors with more aggressive features," said Porter.
"Additional studies are needed to examine the risk factors for triple negative tumors, and why black women have this increased risk," said Lund. "Our results are provocative and carry the message that African-American women might be at higher risk for worse breast tumors and at an earlier age."
Annual Meeting of the American Association for Cancer Research, April 3, 2006, Washington, DC