Study: Prevalence of BRCA founder mutations in Bahamian women
Summary
The Bahamas has the highest known frequency of BRCA mutations among people diagnosed with breast cancer. This study reviewed whether population-based BRCA testing (testing everyone regardless of family or personal history of cancer) would be an effective approach for finding mutation carriers in the Bahamas. (3/4/19)
Relevance
This article is most relevant for Bahamanian women
Relevance: Medium-High
Strength of Science: Medium-High
Research Timeline: Post Approval
Media Ratings
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Who covered this study?
Eyewitness
Why are so many Bahamian women getting breast cancer?
This article rates 3.5 out of 5 stars
Contents
| At a glance | Questions for your doctor |
| Findings | In-depth |
| Media | Resources |
STUDY AT A GLANCE
This study is about:
Whether population-based testing (testing everyone regardless of family or personal history of cancer) would be an effective approach for finding mutation carriers in the Bahamas.
Why is this study important?
The Bahamas has the highest percentage of breast cancer patients who test positive for a mutation. Prior studies have shown that over 25 percent of patients with breast cancer in the Bahamas have a or mutation. Experts have proposed testing all women in the Bahamas with breast or ovarian cancer for mutations.
Study findings:
Over 1,800 unaffected Bahamian women underwent genetic testing. Of these:
- 705 women reported having a family history of breast or ovarian cancer.
- 20 (2.8%) of these women had a mutation.
- 1089 women reported no personal or family history of breast or ovarian cancer.
- Only one (0.09%) of these women had a mutation.
- 53 women reported having a relative who tested positive for a mutation.
- 20 (37.7%) of these women had the familial mutation.
What does this mean for me?
This study suggests that in addition to testing women diagnosed with cancer, all Bahamian women with a family history of breast or ovarian cancer should also be offered genetic testing. If you are a woman from the Bahamas with a family or personal history of breast or ovarian cancer, you should speak with your doctor about genetic testing for a or mutation.
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Posted 3/4/19
References
Trottier M, Lunn J, Butler R, Curling D, Turnquest T, Francis W, Halliday D, Royer R, Zhang S, Li S, Thompson I, Donenberg T, Hurley J, Akbari MR, and Narod SA. Prevalence of founder mutations in the and genes among unaffected women from the Bahamas. Clinical Genetics 2016. 89(3):328-31.
Akbari MR, Donenberg T, Lunn J, Curling D, Turnquest T, Krill-Jackson E, Zhang S, Narod SA, and Hurley J. The spectrum of and mutations in breast cancer patients in the Bahamas. Clinical Genetics. January, 2014. 85(1): 64-67.
Donenberg T, Lunn J, Curling D, Turnquest T, Krill-Jackson E, Royer R, Narod SA, and Hurley J. A high prevalence of mutations among breast cancer patients from the Bahamas. Breast Cancer Research and Treatment. 2011. 125(2):591-6.
Disclosure
FORCE receives funding from industry sponsors, including companies that manufacture cancer drugs, tests and devices. All XRAYS articles are written independently of any sponsor and are reviewed by members of our Scientific Advisory Board prior to publication to assure scientific integrity.
This article is relevant for:
Bahamanian women
This article is also relevant for:
people with triple negative breast cancer
people with ER/PR + cancer
people with breast cancer
people with metastatic or advanced cancer
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IN-DEPTH REVIEW OF RESEARCH
Study background:
The Bahamas has the highest prevalence of mutations among breast cancer patients. In one study, one of the six founder mutations was identified in 49 (23%) of 214 unselected Bahamian breast cancer patients. In a follow-up to this study, researchers conducted full sequencing for and for the 156 patients who did not have a known founder mutation. Four of these patients were found to have a novel in BRCA2; five other unique mutations in and were also identified. In total, mutations were discovered in 58 of the 214 patients (27%). This prevalence far exceeds that of any other population.
In comparison, the reported prevalence in women is between 1% and 2% , with three known founder mutations accounting for the majority of mutations in this population. NCCN guidelines recommend testing for unselected Jewish women who have a personal history of breast cancer. Many genetics experts believe that the high prevalence of mutations in Jewish women and the ability to test for specific founder mutations makes population-based screening cost effective. (It is important to note that not all women with a mutation have a family history of breast and/or ovarian cancer. This is especially true for women with a limited number of female relatives.)
Because the prevalence of mutations among breast cancer patients in the Bahamas is higher than any other population, researchers sought to determine whether population-based testing is an effective approach to testing in the Bahamas.
Researchers of this study wanted to know:
If they could generate evidence to help inform an effective testing policy for Bahamian women.
Population(s) looked at in the study:
These researchers screened a large sample of Bahamian women with no personal history of breast or ovarian cancer. These included both women with and women without a family history of cancer.
Personal and family histories of cancer were collected during pre-test genetic counseling.
A total of 1,921 unaffected Bahamian women provided a saliva sample from which was isolated. Of these women, 44 were not screened for one of the seven founder mutations due to low quality DNA; 30 other participants were excluded because their family cancer history was unknown.
Study findings:
A total of 1,847 unaffected Bahamian women underwent genetic testing:
- Among the 705 (38.2%) women who reported having a family history of breast and/or ovarian cancer, 20 (2.8%) had a mutation.
- Among the 1,089 women who reported no personal or familial history of breast and/or ovarian cancer, only one (0.09%) had a mutation.
- Among the 53 women who reported having a relative with a Bahamian founder mutation, 20 (37.7%) had a mutation.
- 41 mutations were identified.
In this study, 2.8% of women with a first- or second- degree relative with breast or ovarian cancer had a Bahamian .
Limitations:
The patients in this study-mostly were employees of a large resort-were self-selected and did not represent a random sample. Participants were asked about their Bahamian ancestry, however, this information was not verified. Finally, testing in this study was limited to the seven Bahamian founder mutations; participants may have had other deleterious mutations.
Conclusions:
The results of this study support a policy to extend genetic testing for the seven Bahamian and founder mutations to all Bahamian women with a family history of breast or ovarian cancer.
It is important to note that unaffected Bahamian women without a family history of breast or ovarian cancer rarely have a mutation (0.09% in this study). It is unclear why the prevalence of mutations in unselected breast cancer patients would be so high compared to a relatively low prevalence in the general population.
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Posted 3/4/19
Expert Guidelines
The National Comprehensive Cancer Network has guidelines on who should undergo genetic counseling and testing. If you have been diagnosed with breast cancer, you should speak with a genetics expert about genetic testing if any of the following apply to you:
- You have a blood relative who has tested positive for an
- You have any of the following:
- Breast cancer at age 50 or younger
- Male breast cancer at any age
- Ovarian cancer at any age
- at any age
- Two separate breast cancer diagnoses
- Eastern European Jewish ancestry and breast cancer at any age
- Lobular breast cancer and a family history of diffuse gastric cancer
- For treatment decisions for people with breast cancer or people with early , breast cancer who are at high-risk for recurrence
- Testing of your tumor shows a mutation in a gene that is associated with
OR
- You have one or more close family members who have had:
- Young-onset or rare cancers
- Breast cancer at age 50 or younger
- Male breast cancer, ovarian cancer, pancreatic cancer, or cancer at any age
- Two separate cancer diagnoses
- prostate cancer or cancer that is high-risk or very-high-risk group.
The American Society of Breast Cancer Surgeons (ASBrS) released guidelines in 2019 that recommend all women diagnosed with breast cancer have access to genetic testing for inherited mutations in breast cancer genes.
If you are uncertain whether you meet the guidelines above and you are interested in or considering genetic testing, you should speak with a cancer genetics expert.
Updated: 07/28/2023
Questions To Ask Your Doctor
- I am Bahamian. Should I be tested for a mutation?
- I have cancer in my family. Can you refer me to a genetic counselor?
Related Resources
Who covered this study?
Eyewitness
Why are so many Bahamian women getting breast cancer?
This article rates 3.5 out of 5 stars