The gene mutation BRCA1, which is known to increase the risk of breast cancer, is prevalent among Hispanics and young African-American women with breast cancer, says a report in the Journal of the American Medical Association (JAMA).
The mutation is known to heighten the risk for Ashkenazi Jews, so the new ethnic findings are something of a surprise, note the researchers.
"We found that the Hispanic women had a higher prevalence of the harmful BRCA1 mutation than white women, and the highest prevalence was among young African-American women," says study author Esther John, Ph.D., a research scientist at the Northern California Cancer Center in Fremont, California.
"The prevalence of the BRCA1 mutation is different in different racial and ethnic groups," explains Dr. John.
The study assessed the prevalence of the BRCA1 mutation among 3,181 women with breast cancer.
The researchers found that Ashkenazi Jewish women with breast cancer had the highest rate of the BRCA1 mutation, at 8.3 percent.
For Hispanic women with breast cancer, the rate was 3.5 percent. Among non-Hispanic Caucasians, the rate was 2.2 percent, and among Asian women it was 0.5 percent.
For all African-American women, the rate of the mutation was 1.3 percent, but for those under 35 who had breast cancer, the rate was 16.7 percent, Dr. John's group found.
Among the surprises in the study was that Hispanic women were more likely to have a particular mutation that is also common in Ashkenazi Jews, notes Dr. John. She says that Spanish ancestry may account for this.
The researchers speculate that Sephardic Jews, who settled in Spain, could have shared the mutation with Ashkenazi Jews, who settled in central and Eastern Europe.
The prevalence of the BRCA1 mutation in young African-American women with breast cancer was also unexpected, since the overall rate of the mutation is low among African-American women of all ages, says Dr. John.
However, this finding could explain why when young African-American women get breast cancer it tends to be an aggressive form of the disease, which is consistent with cancers that involve BRCA1 mutations.
Dr. John notes that, because BRCA1 mutations are rare, not all women need to be tested for mutations.
However, women who have a family history of breast cancer or who are diagnosed with breast cancer when they are under 35 might want to be tested, she says.
"Women in all ethnic/racial populations would benefit from testing," she says.
One expert believes the findings in the study mirror what she has been seeing in a diverse urban population of women with breast cancer.
"This study supports what I've been finding in my clinical practice," says Dr. Christine Pellegrino, a breast cancer specialist at Montefiore Medical Center in New York City.
Dr. Pellegrino believes in genetic screening for all women who develop breast cancer early.
"There should be a vigorous, well-defined, screening procedure for the female relatives of these women," she says. "There should be widespread use of genetic counseling in these young patients."
Young women with the BRCA1 mutation who have had breast cancer are at risk for a recurrence of their cancer and also of developing ovarian cancer, says Dr. Pellegrino.
"These women need to be closely monitored," she adds.
Another expert agrees that many younger women with breast cancer have a genetic mutation, regardless of their ethnic or racial background.
"Whatever your ethnicity or your race, if you have a high-risk profile - that is, early breast cancer - it predicts the likelihood of genetic mutations across all ethnicities and races," says Dr. Jeffrey N. Weitzel, at the City of Hope Comprehensive Cancer Center in Duarte, California.
However, Dr. Weitzel notes that this latest study does not take BRCA2 mutations into account, which also increase the risk for breast cancer.
"So some of these numbers are underestimates," he explains. "BRCA2 usually accounts for about a third more cases in each group.”
Always consult your physician for more information.
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In 1990, DNA linkage studies on large families with certain characteristics identified the first gene associated with breast cancer.
Scientists named this gene “breast cancer 1” or BRCA1 (pronounced brak-uh). BRCA1 is located on chromosome 17. Mutations in the gene are transmitted in an autosomal dominant pattern in a family.
Since it was clear that not all breast cancer families were linked to BRCA1, studies continued and in 1994, scientists discovered another gene (similar to BRCA1) and named it BRCA2. BRCA2 is located on chromosome 13.
Mutations in this gene are also transmitted in an autosomal dominant pattern in a family.
Both BRCA1 and BRCA2 are tumor suppressor genes that usually have the job of controlling cell growth and cell death. Everyone has two BRCA1 (one on each chromosome #17) and two BRCA2 genes (one on each chromosome #13).
When a person has one altered or mutated copy of either the BRCA1 or BRCA2 gene, their risk for various types of cancer increases.
Both copies of a tumor suppressor gene must be altered or mutated before a person will develop cancer. In hereditary breast ovarian cancer (HBOC) syndrome, the first mutation is inherited from either the mother or father and is therefore present in all cells of the body. This is called a germline mutation.
Whether a person who has a germline mutation will develop cancer and where the cancer(s) will develop depends upon where (which cell type) the second mutation occurs.
For example, if the second mutation is in the ovary, then ovarian cancer may develop. If it is in the breast, breast cancer may develop.
The process of tumor development actually requires mutations in multiple growth control genes. Loss of both copies of BRCA1 or BRCA2 is just the first step in the process.
What causes these additional mutations to be acquired is unknown. Possible causes include chemical, physical, or biological environmental exposures, or chance errors in cell replication.
Some individuals who have inherited a germline BRCA1 or BRCA2 mutation never develop cancer because they never get the second mutation necessary to knock out the function of the gene and start the process of tumor formation.
This can make the cancer appear to skip generations in a family, when, in reality, the mutation is present.
Persons with a mutation, regardless of whether they develop cancer, however, have a 50/50 chance to pass the mutation on to the next generation.
It is also important to remember that the BRCA1 and BRCA2 genes are not located on the sex chromosomes. Therefore, mutations can be inherited from the mother or the father’s side of the family.
Always consult your physician for more information.