It may help explain why black women have higher rates of breast cancer at young ages, a more aggressive form of the disease, and worse survival. It doesn't mean that all black women are at risk or even that all blacks with cancer need genetic counseling or testing, said the study's leader, Dr. Jane Churpek of the University of Chicago.
Experts offer some advice about what to make of this information:
Q. What are the genes?
A. Mostly BRCA1 and BRCA2. Everyone has two copies of these genes, and a mutation in one can give a woman up to an 87 percent risk of developing breast cancer and up to a 54 percent risk for ovarian cancer. Sixteen other genes also can raise risk but are thought to be less common.
Q. Why might blacks have high risk?
A. African-Americans' genes are more diverse than those of many other racial and ethnic groups. Most of the mutations identified in this study were novel, or unique to each woman, Churpek said. It's possible that more detailed tests in whites and other groups might find a higher prevalence of mutations than previous studies have found in them, too.
Q. Should more black women be tested?
A. National guidelines do not specify any groups that should be tested except Eastern European (Ashkenazi) Jewish women with breast or ovarian cancer or a close relative who has had one of those diseases. Genetic counseling should be offered to black women who develop breast cancer before age 50, who have a close relative with the disease, or who have "triple-negative" breast cancer. Triple negative means tumors that are not fueled by estrogen, progesterone or the gene that the drug Herceptin targets.
Q. What can be done if a gene mutation is found?
A. Women who find the mutation after they have breast cancer may want to consider removing both breasts or their ovaries. Those who are screened before cancer develops can consider more frequent screening and prevention measures ranging from hormone-blocking drugs to removal of breasts and ovaries. They also can let relatives know about potential family risk.
Q. Why did this study find so many more gene flaws?
A. Standard tests look for just a few common mutations in BRCA1 and BRCA2. The tests cost around $3,000, and insurance will often cover them if a woman has a family history suggesting high risk. A second $750 test is needed to look for a different type of genetic flaw. That test often is not done or covered by insurance.
In the Chicago study, researchers decoded, or sequenced, all 18 genes tied to breast cancer risk, so it could pick up all types of mutations in any of them.
Breast cancer: http://www.cancer.net/cancer-types/breast-cancer
Marilynn Marchione can be followed at http://twitter.com/MMarchioneAP