The formula doctors use to calculate a woman's risk of breast cancer underestimates the danger for black women most of the time and especially...

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WASHINGTON — The formula doctors use to calculate a woman’s risk of breast cancer underestimates the danger for black women most of the time and especially for those age 50 and older — the age when they are most likely to benefit from screening tests and protective drugs, according to the first major reassessment of the widely used tool.

“We’ve been concerned about the assumptions we had to make for African-American women and other racial and ethnic groups for some time,” said Mitchell Gail of the National Cancer Institute, who led the re-evaluation of the formula he himself developed. “It turns out that we have been underestimating the risk for African-American women.”

The advance could have broad implications for many black women, prompting them to reconsider the danger they face from a disease that is women’s leading cause of cancer and second-leading cancer killer. That could lead to more women undergoing mammograms and other examinations to detect the disease in its earliest, most treatable stages, taking drugs such as tamoxifen to reduce their risk, and signing up for studies evaluating better warning signs or risk-reducing medicines.

“This could very much change the way we counsel African-American women,” said Nancy Davidson, a breast-cancer expert who heads the American Society of Clinical Oncology.

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The new findings, published online Tuesday by the Journal of the National Cancer Institute, are the latest revelation about how breast cancer and other diseases can affect racial groups differently. Growing evidence suggests that breast cancer tends to be much more aggressive and deadly among black women, which could help explain why they are more likely to die from it even though fewer of them get it. More than 19,000 African-American women receive breast-cancer diagnoses each year, and nearly 6,000 die from it.

“This is extremely significant,” said Lovell Jones, director of the Center for Research on Minority Health at the University of Texas M.D. Anderson Cancer Center. “This is emblematic of a broader problem, which is we tend to make the assumption that one size fits all. One size does not fit all.”

The new research examined the Breast Cancer Risk Assessment Tool, more commonly known as the Gail model after the government biostatistician who developed it in 1989. Doctors calculate a woman’s risk by plugging in variables such as the age they started having their period or had their first child and whether a mother or sister has had the disease.

Because the model was based largely on data collected from about 240,000 white women, Gail and his colleagues decided to try to develop a more accurate alternative using data collected more recently on more than 3,200 black women, including more than 1,600 who had breast cancer.

The researchers then tested the new version and showed that it would have accurately predicted how many African-American women in the federal government’s Women’s Health Initiative would have developed breast cancer. Overall, the old model classified only 14.5 percent of black women as candidates for the prevention trial, whereas the new model would classify more than twice as many — 33.3 percent — as eligible.

Based on the findings, Gail and his colleagues recommended that doctors start using the new model for their African-American patients. The National Cancer Institute plans to use the new model to update its calculator, which is available online at

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