TUESDAY, June 6, 2006 (HealthDay News) -- Premenopausal black women are twice as likely to get basal-like breast tumors -- a particularly virulent form of the disease -- than other women, either black or white, a new study found.
Premenopausal black women also have a lower incidence of less aggressive tumors.
Both discoveries may help explain why black women under age 50 have a 77 percent higher death rate from breast cancer than white women of the same age, the researchers said.
The findings, in the June 7 issue of the Journal of the American Medical Association, 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," said 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."
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," Brooks said.
Although black women have a lower incidence of breast cancer, their mortality rate is much higher than white women. And the disparity is even more striking in younger black women.
"Black women at younger ages have a higher mortality," said Dr. Len Lichtenfeld, deputy chief medical officer at the American Cancer Society.
In 2005, scientists from the same research team published data first identifying the basal-like subtype. "Now, in essence, we had a new type of breast cancer," said study co-author Charles Perou, an 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 black, breast cancer databases in the United States, to see if certain segments of women had a higher incidence of the basal-like subtype.
Perou and his colleagues used 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 black women, compared to only 14 percent among postmenopausal black women and 16 percent among whites of any age.
"This aggressive and newly described subtype of breast tumor was about twice as frequent in younger African-American women," Perou said.
On the other hand, a less aggressive form of breast cancer, the luminal A subtype, was less prevalent among premenopausal black women -- 36 percent, compared to 59 percent in postmenopausal black women and 54 percent in whites.
"This is something truly biologically different," Lichtenfeld said. "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," Lichtenfeld said. "The ultimate goal is to be able to take all of these observations and be able to target them specifically for treatment."
Perou said his laboratory has already identified a potential target and therapy that is currently in early trials.
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