Breast Cancer in African-American Women Studied
African-American women who are premenopausal are twice as likely to get a certain type of breast tumor, one that is a particularly virulent form of breast cancer, than other women, according to a study reported in the Journal of the American Medical Association (JAMA).
Premenopausal African-American women also have a lower incidence of less-aggressive tumors.
Both discoveries may help explain why African-American women under age 50 have a 77 percent higher death rate from breast cancer than Caucasian women of the same age, the researchers say.
The findings represent a major step in the drive to identify different breast cancers and find appropriate individual therapies.
"What we thought was one disease is actually multiple, different diseases," says Dr. Jay Brooks, chairman of hematology/oncology at Ochsner Health System in Baton Rouge, La., who was not involved with the new study.
"We're beginning to learn and characterize the cancers in better ways so that we can then predict who needs more or less treatment," says Dr. Brooks.
Eventually, this understanding should translate into better, more targeted therapies.
"This is the beginning of characterizing, and then we need to be able to translate characterizing into better therapeutic options," says Dr. Brooks.
Although African-American women have a lower incidence of breast cancer, their mortality rate is much higher than Caucasian women.
And the disparity is even more striking in younger African-American women.
"Black women at younger ages have a higher mortality," explains Dr. Len Lichtenfeld, deputy chief medical officer at the American Cancer Society.
In 2005, researchers from the same team published a report that first identified what is called a “basal-like” subtype.
"Now, in essence, we had a new type of breast cancer," remarks Charles Perou, Ph.D., an author of the new study, assistant professor of genetics and pathology at the University of North Carolina, Chapel Hill, and a member of the school's Lineberger Comprehensive Cancer Center.
For the new study, the researchers used data from the Carolina Breast Cancer Study, one of the largest African-American breast cancer databases in the US, to see if certain segments of women had a higher incidence of the basal-like subtype.
Dr. Perou used a special test called immunohistochemistry (IHC) profiling to identify breast cancer subtypes in tissue from 496 tumors available from the database.
Basal-like breast cancers represented 39 percent of all breast cancers among premenopausal African-American women, compared to only 14 percent among postmenopausal African-American women and 16 percent among Caucasians of any age.
"This aggressive and newly described subtype of breast tumor was about twice as frequent in younger African-American women," explains Dr. Perou.
On the other hand, a less aggressive form of breast cancer, called the luminal A subtype, was less prevalent among premenopausal African-American women - 36 percent, compared to 59 percent in postmenopausal African-American women and 54 percent in Caucasians.
"This is something truly biologically different," notes Dr. Lichtenfeld. "They're finding genetic patterns that are different in younger African-American women. It's an important step. It answers a question that's real."
Unfortunately, basal-like breast cancer does not respond to some of the newer targeted therapies for breast tumors.
Treatment is still centered on surgery and chemotherapy. But researchers are hoping that more targeted therapies in development will prove to be effective against this particular subtype of the disease.
"In the past we had a one-size-fits-all approach to cancer," says Dr. Lichtenfeld. "The ultimate goal is to be able to take all of these observations and be able to target them specifically for treatment."
Dr. Perou says his lab has already identified a potential target and therapy that is currently in early trials.
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