What are BRCA1 & BRCA2 Genes?
While every woman has about a 12% risk to develop breast cancer, the risk is higher when a woman has a variation in a certain geneA sequence in the DNA which can be passed down from parent to child. Genes helps determine physical and functional traits for the body.. In the mid 1990’s, researchers found that mutations in the BRCA1 and BRCA2 genes increase a woman’s, and sometimes a man’s, risk of breast cancer. Since then, other genesA sequence in the DNA which can be passed down from parent to child. Genes helps determine physical and functional traits for the body. have been identified as associated with an increased risk of breast cancer. BRCA1A gene which, when damaged or mutated, can put a person at a greater risk of developing breast and/or ovarian cancer. and BRCA2A gene which, when damaged or mutated, may put a woman at a greater risk of developing breast and/or ovarian cancer. This gene is also thought to raise the risk for breast cancer in men. remain the genes with the highest risks. Knowing if you carry a variation in one of these genes can help you and your healthcare provider lower your risk of breast cancer.
Are There Increased BRCA Mutations in Women with African Ancestry?
Certain geneticInherited characteristics. changes are found more often in specific ethnic groups, such as the large percentage of Ashkenazi Jews with a mutated BRCA gene. However, research on hereditary breast cancer has not included as many women with African ancestry as women with European ancestry. For that reason, less is known about the risk for women from these ethnic groups to have a genetic mutation that increases the risk of breast cancer.
A study by one of the larger genetics laboratories (Myriad Genetics) found that 15.9% of African American women with breast cancer had a BRCA mutation, but only 12.1% of Europeans, leading the researchers to conclude that the rate of BRCA mutations in African Americans is at least equal to the European rate and may be higher (1).
One of the complications of studying high-risk breast cancer genes is the significant genetic variety among African Americans. So a study of mutations in African American women is, in reality, of study of many different ethnic groups. When researchers are able to identify specific subgroups, differences are seen. One study reported a higher incidenceIncidence refers to the occurrence of new cases of disease or injury in a population over a specified period of time. of BRCA mutations among women from Nigeria and the Bahamas than among women with ancestry from other African countries (2)(3).
Triple-Negative Breast Cancer
The characteristics of hereditary breast cancer include: younger age of onset (30s and 40s), family history of breast and/or ovarian cancer, and triple-negative breast cancer.
The incidenceIncidence refers to the occurrence of new cases of disease or injury in a population over a specified period of time. of triple-negative breast cancer in African American women is higher than in Caucasian women, possibly due partly to a higher BRCA mutation rate. A 2015 study found that among African American breast cancer patients who were young, had triple-negative breast cancer, and had a positive family history, 25% had a hereditary breast cancer mutation (4). This is higher than the BRCA rate among Caucasian woman, and emphasizes the importance of offering genetic testing to young African American triple negative breast cancer patients with a positive family history.
African American Women & Uncertain Genetic Variants
Approximately 10-15% of genetic tests will identify a “variant of uncertain significance” or a VUS (5). This is a genetic change that is not common in the general population—most people don’t have it, but it’s not necessarily abnormal. Variations in our genes are common. We all have many genetic variants that result in our different characteristics, or, don’t have any effect on us at all. Variations are generally classified by labs as pathogenic (risk of disease is increased) or benignNot harmful; not cancerous (referring to a cell or mass). (risk is not increased).
Variations observed in cancer-related genes are studied carefully to determine if they increase the risk of cancer or are benignNot harmful; not cancerous (referring to a cell or mass).. This involves following a variant through multiple generations of a family to study whether or not the individuals affected with cancer also have the variant. If the variant carriers have cancer and their non-carrier relatives do not, that is evidence that the variant is pathogenic. Alternatively, if multiple unaffected relatives have the variant and relatives with cancer do not have the variant, that is evidence that the variant is benign.
These types of studies require large numbers of participants, as a variant cannot be classified as pathogenic or benign until it is observed multiple times in multiple families. If a variant has only been reported a few times, there just isn’t enough information to classify it as benign or pathogenic, and it will be classified as a VUS until more data is available.
Because fewer woman with African heritage have had genetic testing or participated in research studies, there is a smaller database from which to draw information to help classify a variant, so more remain classified as VUS’s in this population. As more non-European individuals are tested, more data will be available to help resolve VUS’s. Approximately 90% of VUS’s are eventually reclassified as benign (no increased risk of cancer)(6).
Undertesting in African American Communities
Women in African American communities are offered genetic testing and end up being tested much less often than women in other communities (7). This may be because their healthcare providers are calculating that their personal or family history does not meet the criteria to be tested.
Current guidelines state that any woman diagnosed with breast cancer at age 45 or younger should be referred for genetic testing. If they are over 45, they are referred only if they have a triple negative diagnosis, or a 1st or 2nd degree relative with breast, ovarian or pancreatic cancer. However, one study on mutations in African American women found that if women aged 46-50 were referred only when they met testing criteria based on their personal or family history of cancer, a significant number of mutation carriers would be missed. 41% of mutation carriers had no first and/or second-degree relative with breast and/or ovarian cancer, and would have been missed if current guidelines had been followed. This study concluded that “it is appropriate to recommend BRCA testing in all African American women with invasive breast cancer diagnosed before age 50, regardless of family history.” (8)
It is possible that a patient’s knowledge of their family history is incomplete or incorrect. Family history may be unreliable if relatives kept their diagnosis a secret, if one parent left and contact was lost with that side of the family, or if the family (especially paternal) is very small and has few or no females.
It is important to remember that a breast cancer gene mutation can be inherited from one’s mother or father, and it is important to try to collect health history information from both sides of the family. if you’ve been told you are not eligible for testing, speak with a genetic counselor to go over your family history and discuss what testing options may be available.
Keep in mind:
- In many cases, health insurance plans will cover the costs of genetic testing when a person meets certain criteria, or when a specialist is strongly suspicious of a hereditary mutation.
- At-home testing kits are available, but are limited in scope and not considered clinically useful.
- If your genetic testing is negative, but you have a significant family history of breast cancer, you will still want to be followed closely by your doctors.
- Your father’s family history is as important as your mother’s.
- Knowing about ovarian, pancreatic, prostate and colon cancer in the family is also important when assessing the risk of breast cancer. Report any cancer history to your healthcare provider.
What You Can Do
No matter your ethnicity or heredity, there are a variety of ways you can improve your breast cancer risk levels and increase your likelihood of early detection.
- Collect as much family history as possible.
- If possible, determine your specific ethnicity.
- Find out specific information about relatives with cancer (How old were they when they were diagnosed? Was the breast cancer bilateralOn both sides.? What type of treatment did they get? Were they diagnosed again? Is there male breast cancer in the family?)
- Do a monthly breast self-exam to get to know your body and detect lumps early.
- Every year, if you are over 40, schedule a mammogram
- Reduce your risk levels by staying at a healthy weight, exercising, enjoying a plant-based diet, and avoiding smoking, alcohol, and high fat diets.
Remember, regardless of your breast cancer risk levels today, there is always something you can do to improve your odds. Your health is in your hands!
- “BRCA1 and BRCA2 mutations in women of different ethnicities undergoing testing for hereditary breast-ovarian cancer,” Cancer, 2009
- “High prevalence of BRCA1 and BRCA2 mutations in unselected Nigerian breast cancer patients,” International Journal of Cancer, 2012
- “The spectrum of BRCA1 and BRCA2 mutations in breast cancer patients in the Bahamas,”Clinical Genetics, 2014
- “Inherited predisposition to breast cancer among African American women,” Breast Cancer Research and Treatment, 2015
- “Understanding of BRCA VUS genetic results by breast cancer specialists,” BMC Cancer, 2015
- “Prevalence of Variant Reclassification Following Hereditary Cancer Genetic Testing,” JAMA, 2018
- “Racial/Ethnic Disparities in BRCA Counseling and Testing: a Narrative Review,” Journal of Racial and Ethnic Health Disparities, 2019
- “A High Frequency of BRCA Mutations in Young Black Women with Breast Cancer from Florida,” Cancer, 2015