Gene Mutations Linked to Breast Cancer in Black Women

Study findings suggest genetic testing would be worthwhile, experts say

TUESDAY, Oct. 18, 2005 (HealthDay News) -- Doctors have known for a decade that women with certain genetic mutations are at higher risk of breast cancer, and Jewish women of Eastern European descent are especially likely to have these mutations.

Now, a new study has found that black women also have a high rate of mutations in the BRCA1 and BRCA2 genes, but of a different type.

While information about Eastern European (Ashkenazi) Jews has grown, "there really is a paucity of data in the other minority communities, especially African-Americans," said Dr. Olufunmilayo Olopade. She is lead author of the new study and a professor of medicine and human genetics at the University of Chicago Medical Center.

"Given that African-Americans are more likely to get breast cancer at a young age, it really becomes even more important for us to do a better job of risk assessment," Olopade said.

The study findings appear in the Oct. 18 issue of the Journal of the American Medical Association.

The researchers primarily evaluated people who came to the University of Chicago Cancer Risk Clinic between February 1992 and May 2003. They also evaluated families who visited other high-risk clinics, including those in Chicago and San Francisco.

The families had two or more cases of breast cancer, ovarian cancer, or both among first- and second-degree relatives.

Women with BRCA1 or BRCA2 mutations are three to seven times more likely to get breast cancer than those without the mutations, according to the National Cancer Institute.

The "mutation spectrum" was different between families of European and African descent, the researchers found. Compared with non-Jewish, non-Hispanic whites, women of African descent had a lower rate of one type of BRCA1 and BRCA2 mutations, called deleterious, but a higher rate of another type, called sequence variations.

In all, 28 percent of the black women tested positive for a deleterious mutation in one of the two genes, Olopade said, compared to 46 percent of non-Hispanic, non-Jewish whites. But 44 percent of the black women had sequence variation mutations, compared to 11.5 percent of the non-Jewish, non-Hispanic families.

The deleterious mutations were highest, at 69 percent, in the Eastern European Jewish families. A total of 155 families were studied, the researchers said.

"High-risk African-American women (with a family history of breast or ovarian cancer) may benefit from genetic testing," Olopade said.

"This is the first paper to show that the spectrum of mutations reflects ancestry," Olopade said. "The study is the first to compare African-American women with women of European descent. What we find is, if they have the same family history, when you test them they are likely to have the mutation."

More study is needed on other racial and ethnic populations, she said, including Asians and Hispanics.

The key point for black women, she said, is: "If you have a family history of breast cancer, go to a doctor and demand genetic counseling and testing."

What the study seems to show is that "there are sequence variations related to BRCA1 and BRCA2 that are related to breast cancer in African-American women," said David Nerenz, acting director of the Center for Health Services Research at the Henry Ford Health System in Detroit.

The implication is that testing for mutations would prove as effective in blacks as in whites, he added.

But, Nerenz said, the study begs more questions.

"We don't know whether large-scale applications of genetic testing for susceptibility for breast cancer will save lives, and we don't know whether it will be cost-effective if it does save lives," he said. "We don't know this yet for African-American women and for women in general."

More information

To learn more about BRCA1 and BRCA2, visit the National Cancer Institute.

SOURCES: David Nerenz, Ph.D, acting director, Center for Health Services Research, Henry Ford Health System, Detroit; Olufunmilayo Olopade, M.D., professor of medicine and human genetics, University of Chicago Medical Center; Oct. 19, 2005, Journal of the American Medical Association
Consumer News