Women of Ashkenazi Jewish descent who know they have a mutation in the BRCA1 or BRCA2 gene, but decided not to have preventive mastectomy, have better outcomes if they’re diagnosed with breast cancer compared to Ashkenazi Jewish women who don’t know they have a mutation, according to a study.
The research was presented at the European Society of Human Genetics Annual Meeting on June 16, 2019. Read the abstract of “Impact of germline BRCA mutation identification on subsequent breast cancer stage, therapy and survival — implications for routine screening.”
Gene mutations linked to breast cancer
Two of the most well-known genes that can mutate and raise the risk of breast and/or ovarian cancer are BRCA1 and BRCA2. Women who inherit a mutation in either of these genes — from their mothers or their fathers — have a much higher-than-average risk of developing breast cancer and/or ovarian cancer.
Men with these mutations have an increased risk of breast cancer, especially if the BRCA2 gene is affected, and possibly of prostate cancer.
About 5% to 10% of breast cancers are thought to be hereditary, meaning the cancer is linked to mutations in genes passed from parent to child.
You are substantially more likely to have a genetic mutation linked to breast cancer if:
- You have blood relatives (grandmothers, mother, sisters, aunts) on either your mother's or father's side of the family who had breast cancer diagnosed before age 50.
- There is both breast and ovarian cancer on the same side of the family or in a single individual.
- You have a relative(s) with triple-negative breast cancer.
- There are other cancers in your family in addition to breast, such as prostate, melanoma, pancreatic, stomach, uterine, thyroid, colon, and/or sarcoma.
- Women in your family have had cancer in both breasts.
- You are of Ashkenazi Jewish (Eastern European) heritage.
- You are African American and have been diagnosed with breast cancer at age 35 or younger.
- A man in your family has had breast cancer.
- There is a known breast cancer gene mutation in your family.
Why do Ashkenazi Jewish women have a higher risk of breast cancer?
Ashkenazi Jewish women have a much higher risk of having a founder mutation in the BRCA1 and BRCA2 genes — about a 1 in 40 risk. This is part of the reason why Ashkenazi Jewish women have a much higher-than-average risk of breast cancer.
A founder mutation is a specific gene mutation in a population that was founded by a small group of ancestors that were geographically or culturally isolated. Because the population was isolated, the rate of founder mutations in descendants is much higher than it would be if the population were larger and intermingling with more genetically diverse people.
Even though Ashkenazi Jewish women have a higher risk of breast cancer, genetic testing to screen for mutations linked to breast cancer in all Ashkenazi Jewish women is not the current standard of care.
"The problem is that genetic screening for BRCA [mutations] by a saliva or blood test is not recommended by any medical body or health care organization in healthy Ashkenazi Jewish women without a strong family history,” said Rachel Rabinovitch, M.D., professor of radiation oncology at the University of Colorado School of Medicine and one of the study’s authors. “The way women usually find out they have a BRCA [mutation] is only after they are diagnosed with breast cancer, at which time we've lost the opportunity to offer surgery that could prevent breast cancer or start high-risk breast cancer screening at an age young enough to detect cancers earlier.”
Rabinovitch and her colleagues did this study to see if Ashkenazi women who knew they had a BRCA mutation and were diagnosed with breast cancer had different outcomes than Ashkenazi women who didn’t know if they had a BRCA mutation until after they were diagnosed with breast cancer.
How the study was done
The researchers looked at the medical records of 105 Ashkenazi Jewish women diagnosed with breast cancer between 2005 and 2016 who had a BRCA mutation. None of the women had had preventive mastectomy.
Of the 105 women:
- 42 knew they had a BRCA mutation before they were diagnosed
- 63 women learned they had a BRCA mutation after they were diagnosed
Both groups of women had an average age of about 50 at diagnosis, and both groups had similar rates of BRCA1 (64%) and BRCA2 (36%) mutations.
Compared to women who didn’t know they had a BRCA mutation, women who knew they had a BRCA mutation were more likely to have:
- a strong family history of breast cancer
- previous breast cancer screening
- been diagnosed by imaging, such as a mammogram, rather than clinical symptoms, such as feeling a lump
When looking at the breast cancers, women who knew they had a BRCA mutation were more likely to be diagnosed with cancers that were a lower stage at diagnosis than women who didn’t know they had a BRCA mutation.
There were no differences in tumor grade, hormone-receptor status, or HER2-receptor status between the two groups.
Compared to women who didn’t know they had a BRCA mutation, women who knew about a mutation were:
- less likely to be treated with chemotherapy
- more likely to have a double mastectomy
Overall, knowing BRCA mutation status was linked to a higher likelihood of being diagnosed with stage 0 or stage I breast cancer. The results also hinted that knowing BRCA mutation status might be linked to better survival, but the data were not mature enough to fully support this conclusion.
“We found that women who knew they were BRCA positive and chose to keep their breasts were much more likely to be diagnosed with noninvasive breast cancer, earlier stage invasive breast cancer, and need less morbid cancer therapy; but most importantly their survival was better," Rabinovitch said. She suggested that the results argue for routine BRCA screening in women of Ashkenazi Jewish descent.
"However even among those of us who did the study, we do not agree on when is the best age for genetic screening," she added. "My colleagues who live in Israel suggest it should be done at age 30 — the age at which significant cancer risk begins — but I think that's too late.
"Testing at age 30 is useful for the woman — it's before she is likely to develop breast or ovarian cancer and so offers her the opportunity for surgical prevention or increased cancer screening. However, by that age, many women have made the decision to get pregnant, and you've deprived them of the option to undergo procedures which would prevent passing on the BRCA mutation to their children. While not all women will choose this, I think they should be given the opportunity to do so."
What this means for you
If you are of Ashkenazi Jewish descent, it makes sense to talk to your doctor about your personal risk of breast cancer. When calculating your personal risk, you and your doctor will take into account your family history of breast cancer, your age, your ethnicity, any earlier breast biopsies you’ve had, and your breast density, among other factors.
Based on your risk, your doctor may recommend you have genetic testing. A licensed certified genetic counselor or your doctor can help you understand the test and accurately interpret the results.
If you do have a mutation linked to breast cancer, there are lifestyle choices you can make to keep your risk as low as it can be, including:
- maintaining a healthy weight
- exercising regularly
- limiting alcohol
- never smoking
- eating a diet rich in unprocessed, nutrient-dense foods (foods that have the most vitamins, minerals, and healthy compounds)
There are also more aggressive steps you can take to reduce your risk of breast cancer, including:
- more frequent screening that starts at a younger age
- taking a medicine such as tamoxifen, Evista (chemical name: raloxifene), Aromasin (chemical name: exemestane), or Arimidex (anastrozole)
- removing the healthy breasts and ovaries — called prophylactic or protective surgery — before cancer develops
For more information on genetic testing, including types of genetic tests and how results are reported, visit the Breastcancer.org Genetic Testing pages.
For more information on genes and genetic mutations linked to breast cancer, as well as all the risk-lowering steps you can take if you have a genetic mutation, visit the Breast Cancer Risk Factors: Genetics page in the Breastcancer.org Lower Your Risk section.
To discuss being at high risk for breast cancer with other people, join the Breastcancer.org Discussion Board forum, High Risk for Breast Cancer. If you've tested positive for a mutation linked to breast cancer and would like to talk about this with others who have also tested positive, join the forum, Positive Genetic Test Results.
Written by: Jamie DePolo, senior editor
Reviewed by: Brian Wojciechowski, M.D., medical adviser