Drug-Resistant Breast Cancer Afflicts Blacks

A key insight came last year when a detailed genetic analysis of 496 breast tumors showed that a "basal-like" form of triple-negative cancer was startlingly more common among young black women, accounting for 39 percent of their cancers, compared with 16 percent of white women's.

"We found an important piece of the puzzle," said Lisa A. Carey of the University of North Carolina, who led the study. "This indicates that biology is important."

Other studies subsequently confirmed the findings, including one involving more than 50,000 California women published last month that found triple-negative tumors about twice as often among black women as among white women. It also found that triple-negative is also more frequent in Hispanics than in whites, though still less common than in blacks.

Some researchers, suspecting that the higher rate among African Americans might stem from a genetic predisposition, have begun studying women in parts of Africa. They discovered that triple-negative is extremely common, accounting for some 70 percent of breast cancers in women tested in Nigeria and Senegal, for example.

"This suggests that there may be a genetic contribution," said Olufunmilayo Olopade of the University of Chicago, who is leading the research. "Is it because of genes common to African ancestry? Maybe there's a genetic contribution that we didn't appreciate."

If genetics is important, an individual African American woman's risk probably depends in part on her particular heritage, cautioned Lovell A. Jones, director of the center for research on minority health at the M.D. Anderson Cancer Center.

"One should go back to Africa and find areas where there is a high incidence of this disease," Jones said. "This may not apply to every African American woman, if she's not from those particular areas."

Researchers are planning to study young black breast cancer patients in the Washington, Baltimore and Chesapeake Bay areas and from the parts of West Africa where the ancestors of many are believed to have originated to try to identify the specific genes involved.

"This is the first time there's been an attempt to link a U.S. health disparity to an ancestral African population," said Fatima Jackson, a University of Maryland medical anthropologist.

But other research suggests that social factors may be more crucial. One study published online this week, for example, found that women who did not breast-feed their children are especially prone to triple-negative cancer.

"Our data show that is has nothing to do with genetics but really has to do with environmental factors," said Robert Millikan of the University of North Carolina, noting that black women are less likely than white women to breast-feed.

Olopade and others suspect that the answer will probably be a combination of genes and other factors.