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June 6, 2006 -- Premenopausal black women with breast cancerbreast cancer may be more likely to have a certain genetic pattern than other breast cancercancer patients, new research shows.
The finding may help explain why breast cancer often has a poorer prognosis in black women, write Lisa Carey, MD, and colleagues in The Journal of the American Medical Association.
Breast cancer is the No. 2 cause of cancer deaths for U.S. women, second only to lung cancerlung cancer.
While breast cancer is more common among white women, black women are more likely to die of breast cancer. The black-white gap may stem from genetic and environmental factors, as well as access to medical care, note Carey and colleagues.
Breast Cancer Study
Carey's team studied 496 women in North Carolina who were diagnosed with breast cancer between May 1993 and December 1996.
The women were 20-74 years old when their breast cancers were diagnosed. They reported their race.
The group included 196 black women and 300 women who weren't black. Most nonblack participants were whites; the group also included 14 Native American, Hispanic, Asian-American, or multiracial women.
Carey and colleagues checked participants' data on certain genetic subtypes of breast cancer. "These subtypes differ markedly in prognosis and in the repertoire of therapeutic targets they express," write Carey and colleagues.
Pattern for Premenopausal Black Women
Carey's team found that one of those genetic subtypes -- which they call "basal-like tumors" -- occurred in nearly 40% of premenopausal black women they studied.
In comparison, that genetic subtype was seen in 14% of postmenopausal black women and 16% of nonblack women of any age, the study shows.
That particular genetic subtype involved tumors that aren't sensitive to estrogen, a hormone that stimulates some, but not all, breast cancers.
None of the black women (and few of the nonblack women) in Carey's study tested positive for the BRCA1 genetic mutation, which is linked to a higher risk of breast cancer and ovarian cancerovarian cancer. The study's results don't cover BRCA2, another genetic mutation linked to breast cancer.
Cautioning that their findings need to be confirmed, Carey's team calls for long-term survival studies in patients with various genetic subtypes of breast cancer.
Clinical trials are also needed to find therapies for basal-like breast cancer, "especially for young, black women," write Carey and colleagues.
SOURCES: Carey, L. The Journal of the American Medical Association, June 7, 2006; vol 295: pp 2492-2502. American Cancer Society: "Breast Cancer Facts & Figures 2005-2006." News release, JAMA/Archives.