May 19 (UPI) -- African-American and white women share several genetic mutations that increase risk for breast cancer, according to a study published Tuesday by the Journal of the National Cancer Institute.
Researchers at Boston University and the Mayo Clinic found that mutations of the BRCA1, BRCA2 and PALB2 genes, which are known to raise breast cancer risk in white women, including those of Ashkenazi Jewish descent, are also found in African-American women with the disease.
The genetic mutations have been associated with a more than seven-fold higher risk of breast cancer, the researchers noted.
"We also found that mutations in PALB2, RAD51C and RAD51D confer increased risks of estrogen receptor negative breast cancer in the African-American population," study co-author Fergus Couch, the Zbigniew and Anna M. Scheller Professor of Medical Research at the Mayo Clinic, said in a statement.
About one out of every eight women in the United States will develop invasive breast cancer during their lifetimes, according to BreastCancer.org. African-American women tend to be diagnosed at a younger age and are more likely to die from the disease.
However, rates of breast cancer genetic testing are substantially lower in African-American women than in white women, the authors of the JNCI study said. Differences in health recommendations given to African-American women have been identified as one of the drivers of this disparity, they added.
For the study, Couch and his colleagues sequenced germline DNA from 5,054 African-American women with breast cancer and 4,993 age-matched African-American women without cancer, looking for mutations in 23 genes believed to predispose women to the disease. The researchers then estimated the risk of developing breast cancer associated with having a mutation in any of the genes.
They found that more than 7 percent of women with breast cancer, regardless of race, had a mutation in one of the genes, as compared with 2 percent of the controls. Among women with breast cancers that lacked estrogen receptors -- or had estrogen receptor negative breast cancer -- more than 10 percent had a mutation in one of these genes.
In comparison, 5 percent of women with estrogen receptor positive breast cancer had a mutation in the cancer-related genes.
In addition to common mutations of the BRCA1, BRCA2, PALB2, RAD51C and RAD51D, the authors identified four other genetic mutations associated with a more moderate increase in risk for breast cancer among the women in the study. Previous studies of women of African ancestry were too small to identify genetic mutations other than those affecting BRCA1 and BRCA2.
Based on these findings, testing for breast cancer predisposition genes can prevent breast cancer deaths -- both in women who have never had breast cancer and in women with breast cancer -- according to the researchers.
"The multi-gene panels that are currently available to test women diagnosed with breast cancer or women at high risk due to their family history will be useful for African American women," said co-author Julie Palmer, director of Boston University's Slone Epidemiology Center.
"Depending on results of the testing and an individual's own weighing of pros and cons, a woman with a mutation in any of these genes may choose more aggressive screening for cancer, and women with mutations in the high risk BRCA1 and BRCA2 genes may choose removal of her breasts and/or ovaries as a way to prevent initial breast cancer or recurrence," she added.