Two mutations in genes, more commonly found in the Jewish population, are shown to be associated with breast cancer.
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It’s a subject that most women of a certain age are quite alert to. By the age of 40, when most women begin to get screening mammograms, breast cancer enters the realm of possibility.
According to Dr. Nadine M. Tung, director of the Cancer Risk and Prevention Program at Beth Israel Deaconess Medical Center and assistant professor at Harvard Medical School, Ashkenazi Jewish women have an additional concern.
Just by way of being Jewish, is your risk of cancer increased? Dr. Tung said the answer is no. However, “if you’re a Jewish woman and you have a family history of breast cancer, your risk of cancer is higher” than a non-Jewish woman with a similar family history, she said.
Two genes, the BRCA1 and BRCA2, are responsible for the higher risk. While everyone has these genes, certain abnormalities within them—which are more prevalent in Jews—have been shown to increase the risk of breast cancer.
"These are not Jewish genes, there's just a higher chance of finding the abnormality in Jews,” said Dr. Tung. One out of 40 Ashkenazi Jews is born with this abnormality, which is at least 10 times higher than for people who are not Jewish.
Responsible for 5 percent of all breast cancer, and 10-12 percent of breast cancer in Jewish women, these abnormalities also explain a higher portion of cancer in the Jewish population. In addition to breast cancer, the abnormalities also predispose women to ovarian cancer, for which there is no good screening test, said Dr. Tung.
Why the prevalence in Jews? “In pre-biblical times these abnormalities existed, and through intra-marrying within the population they became increased,” Dr. Tung explained. She added that these abnormalities survived through population reduction (e.g., progroms; the Holocaust) and were enriched because Jews reproduced within a shrinking population.
Steps can be taken for early detection. The genetic testing has been available since 1997, and according to Dr. Tung it is available to men as well. “Men are often testing more for the women in their lives, such as their daughters or sisters. However, there is a higher incidence of certain cancers, such as prostate cancer, in men who inherit these mutations. Results can have important implications for cancer screening in these men."
Dr. Judy Garber, who is the Co-Director of Friends of Dana-Farber Genetics and Prevention Program, and a professor of medicine at Harvard Medical School, said that while genetic screening is available, it is widely seen as controversial.
“People get tested because they think they have enough risk to be tested.” Dr. Garber said, “All Jewish women could be tested because the prevalence in the population is not that low, one out of forty, but others think that you should only be tested when you’re ready to learn that you have a mutation.”
Dr. Garber discussed a study done in Israel, where all subjects, whether they had a family history of breast or ovarian cancer or not, were tested. The study found that the genetic abnormality was just as common in both groups.
Still, the controversy over whether everyone should be tested or not persists, and much of it is based in history. Dr. Garber explained that when the prevalence of sickle cell anemia was discovered in the African American population, and a hemoglobin test was recommended, “people in the African American community thought that this was genocide—that people were trying to wipe them out. I bet not everybody thinks differently today.”
Among the concerns Dr. Garber has heard are raised anxiety in the Jewish community, as well as concerns that those with the mutation would be identified as “damaged goods” for marriage.
So, what if you do get tested and an abnormality is discovered? Dr. Tung said that women make different choices. "By age 40, when women have completed child-bearing, those who have inherited a mutation in these genes should remove their ovaries. This will dramatically reduce their risk of ovarian cancer, for which there is no effective screening. Removing one's ovaries also reduces the risk of breast cancer, if performed before menopause, through the lowering of estrogen levels. To reduce the risk of breast cancer some [women] intensify screening, others have preventative mastectomies.”
Dr. Tung reminds women of two main take-home messages. The first is that there is a lot we still don’t know about breast cancer development. “We can only explain about half of inherited breast cancer cases from genes that have been discovered thus far,” she said. Many genes that predispose to the development of breast cancer have not yet been found. The second is that Jewish women are not more likely to develop breast cancer than non-Jewish women, but more of the breast cancer that develops in Jewish women is caused by genes inherited from one parent or the other.