Breast cancer genetic mutations and testing
Inherited genetic mutations that increase the risk of breast cancer
About 5% to 10% of breast cancer cases are thought to be hereditary, meaning that they result directly from gene changes (mutations) passed on from a parent. The most common cause of hereditary breast cancer is an inherited mutation in the BRCA1 or BRCA2 gene. In normal cells, these genes help make proteins that repair damaged DNA. Mutated versions of these genes can lead to abnormal cell growth, which can lead to cancer.
On average, a woman with a BRCA1 or BRCA2 gene mutation has up to a 7 in 10 chance of getting breast cancer by age 80. Women with one of these mutations are more likely to be diagnosed with breast cancer at a younger age, as well as to have cancer in both breasts. Women with one of these gene changes also have a higher risk of developing ovarian cancer and some other cancers. Men who inherit one of these gene changes also have a higher risk of breast and some other cancers.
In the United States, BRCA mutations are more common in Jewish people of Ashkenazi (Eastern Europe) origin than in other racial and ethnic groups, but anyone can have them. Other gene mutations can also lead to inherited breast cancers. These gene mutations are much less common, and most of them do not increase the risk of breast cancer as much as the BRCA genes.
Source: “Inheriting certain gene changes” (American Cancer Society)
Certain gene mutations increase the risk of Triple-Negative Breast Cancer (TNBC)
Mutations in the following genes have been linked to increased risk for breast cancer in women:
- BARD1 (especially triple-negative breast cancer)
- BRCA1 (frequently linked to triple-negative breast cancer)
- CDH1 (frequently linked to lobular breast cancer)
- NF1 (only in people with neurofibromatosis)
- RAD51C (especially triple-negative breast cancer)
- RAD51D (especially triple-negative breast cancer)
Mutations in the following genes may also be linked to increased breast cancer risk, but more research is needed to confirm this.
- BRIP1 (especially triple-negative breast cancer)
- NBN (only in people with a 657del5 mutation)
Mutations in the following genes have been linked to breast cancer risk in men:
Source: “Genes with inherited mutations linked to breast cancer” (FORCE: Facing Hereditary Cancer Empowered)
About BRCA1 and BRCA2 genes
Dispelling myths of BRCA gene mutations
BRCA mutations have been linked to breast, ovarian, pancreatic and prostate cancers, all of which aside from ovarian cancer, can affect men.
A 4-minute video from AstraZeneca.
Understanding BRCA Mutations and Risk
Everyone has the BRCA genes. Their job is to repair errors that occur in your cell’s DNA. If one or both genes you inherited have a mutation, they might let some errors through.
A 4-minute video from the Dr. Susan Love Foundation.
BRCA Genes and Breast Cancer
Without treatment, a woman who is BRCA1 or BRCA2 mutation carrier is seven times more likely to develop breast cancer and 30 more times likely to develop ovarian cancer before the age of 70.
A 3-minute video from the CDC.
My Experience as a BRCA Mutation Carrier
Erika Stallings is a lawyer, writer, and patient advocate based in New York City. In 2014, she learned that she carried a BRCA2 mutation like her mother.
“Despite my risk, I avoided getting tested. I was busy living life. Before I knew it, I was 28 years old, about the same age that my mom was first diagnosed. Looking back, I’m a little embarrassed that I pushed it off. But when you’re young, you feel healthy. You don’t expect these huge hurdles to come up, even if you know you’re at risk.”
“I tried to make an appointment for genetic testing at Memorial Sloan Kettering, but was waitlisted due to a shortage of genetic counselors in the United States. In June 2014, I got an appointment at New York University. I did some volunteer work for a breast cancer organization in New York City, and the executive director helped me get an appointment. If it weren’t for them, I would’ve had to wait another six months. In July, I got the results. I had inherited the BRCA2 mutation. I knew it.”
Stallings underwent a preventative mastectomy later that year.
Source: “My Experience As a BRCA Mutation Carrier”(August 25, 2021)
Disparities in gene mutations?
Black and White Women share same 23 gene mutations that increase the risk of breast cancer
The same genes that increase the risk of breast cancer in U.S. White women also greatly increase breast cancer risk among African American women.
Researchers in 2020 sequenced the germline (inherited) DNA from 5,054 African American women with breast cancer and 4,993 age-matched African American women without cancer looking for mutations in 23 genes linked to a predisposition for cancer. They then estimated the risks of developing breast cancer associated with having a mutation in any of the genes.
These genes include the BRCA1, BRCA2 and PALB2 genes, each of which is associated with a more than seven-fold risk of breast cancer, as well as four other genes associated with a more moderate increase in risk. Previous studies of women of African ancestry were too small to assess genes other than BRCA1 and BRCA2.
“This means that the multi-gene panels that are currently available to test women diagnosed with breast cancer or women at high risk due to their family history will be useful for African American women,” explains Julie Palmer, ScD, (left) of the Boston University School of Medicine.
- Source: “African American and White Women Share Genes that Increase Breast Cancer Risk” on the Boston University School of Medicine website
- See the full text of the scientific paper “Contribution of Germline Predisposition Gene Mutations to Breast Cancer Risk in African American Women” by Julie R Palmer et al.
Similar rates of genetic mutations between Black and White women diagnosed with breast cancer
In a 2021 study of 3,946 Black women diagnosed with breast cancer and 25,287 White women also diagnosed with the disease, the rates of genetic mutations in genes linked to breast cancer were similar.
Among the Black women, 5.65% had a mutation in one of the 12 genes, compared with 5.06% of the White women, a difference that is not statistically different.
The researchers, led by Susan Domchek, MD, (right) of the University of Pennsylvania, concluded that all efforts should be made to ensure equal access to genetic testing to minimize disparities in care and outcomes in women diagnosed with breast cancer.
The study also confirmed that Black women were more likely to be diagnosed with breast cancer at a younger age, more likely to be diagnosed with triple-negative breast cancer, and more likely to be diagnosed with estrogen-receptor-negative breast cancer (which tends to grow faster than hormone receptor-positive cancer).
- Source: “Do Black Women Diagnosed With Breast Cancer Have Higher Rates of Genetic Mutations Than White Women?” by Jamie DePolo on the breastcancer.org website
- See the full text of the scientific paper “Comparison of the Prevalence of Pathogenic Variants in Cancer Susceptibility Genes in Black Women and Non-Hispanic White Women With Breast Cancer in the United States” by Susan M. Domchek et al.(righ
Recent news about breast cancer mutations
Genetic testing to learn about breast cancer risk
Genetic testing to guide breast cancer treatment
Genetic testing may be recommended after a diagnosis of early or metastatic breast cancer. Genetic testing looks for gene mutations in the hereditary genes of a person. Genetic testing may help guide breast cancer treatment. Some breast cancer treatments are only given to people who have certain inherited gene mutations.
Testing also gives a chance to learn if the breast cancer is related to an inherited gene mutation, which can be important information for family members.
Testing for tumor gene mutations may also be done. The tests look at the genes in the cancer cells. For some people with breast cancer, tumor gene testing can help guide treatment.
More at: Genetic Testing After a Breast Cancer Diagnosis (Susan G. Komen)
Who should speak to an expert about genetic testing
Experts recommend that people diagnosed with breast cancer who have any of the following should speak to an expert about genetic testing:
- Triple-Negative Breast Cancer
- diagnosed with breast cancer more than once
- breast cancer diagnosed at age 45 or younger
- male breast cancer
- advanced or metastatic breast cancer
- early stage breast cancer at high risk for recurrence
- a close blood relative who tested positive for an inherited mutation in a gene linked to cancer risk
- close blood male relative diagnosed with breast cancer
- Ashkenazi Jewish ancestry
- lobular carcinoma and a personal or family history of diffuse gastric cancer
For more reasons to seek genetic counseling, see “Genetic testing for people who have been diagnosed with breast cancer” (FORCE: Facing Hereditary Cancer Empowered)
Disparities in genetic testing?
Black women less likely to undergo genetic counseling and testing
About five percent of both Black and white women have a genetic mutation that increases their risk of breast cancer, according to a new study of nearly 30,000 patients.
However, compared to White women, Black women are much less likely to undergo genetic counseling and testing, largely due to differences in physician recommendations or access to care.
“Our efforts should focus on ensuring equal access to testing to minimize disparities in care and outcomes,” said researcher Susan Domchek of Penn Medicine at the University of Pennsylvania (June 11, 2021)
Read more at “Black and White Women Have Same Mutations Linked to Breast Cancer Risk” on the Penn Medicine website (June 11 , 2021)
Racial Disparities Persist in Genetic Testing
Carlette Burton knew she had a family history of cancer, but she never looked into her genetic risk for BRCA-related cancer until she found a concerning lump in her breast during a self check. After her diagnosis, she had genetic testing done and found out that she has a BRCA mutation.
Burton’s mother also had been diagnosed with breast cancer in her 30s. Her grandmother had had breast cancer, too. She is one of five sisters, “but I don’t ever recall a doctor saying we should get tested.”
Read more at “Racial disparities still persist in genetic testing for BRCA-related breast cancer” by Tracey Romero on the Philly Voice website (April 6, 2021)
Recent news about breast cancer genetic testing
Recording your family history
Cancer Family History Questionnaire from cancer.net
Get Genetic Counseling Before Testing
The Centers for Disease Control and Prevention (CDC) says it’s important to get genetic counseling before genetic testing for hereditary breast and ovarian cancer in order to determine whether you and your family are likely enough to have a mutation that it is worth getting tested. Usually, genetic testing is recommended if you have:
- A strong family health history of breast and ovarian cancer
- A moderate family health history of breast and ovarian cancer and are of Ashkenazi Jewish or Eastern European ancestry
- A personal history of breast cancer and meet certain criteria (related to age of diagnosis, type of cancer, presence of certain other cancers or cancer in both breasts, ancestry, and family health history)
- A personal history of ovarian, fallopian tube, or primary peritoneal cancer
- A known BRCA1, BRCA2, or other inherited mutation in your family
Carletta (above) tested negative for BRCA mutations after being diagnosed with breast cancer.
To find genetic counseling services:
- Find a genetic counselor using the National Society of Genetic Counselors directory.
- Find a genetics clinice using the American College of Medical Genetics and Genomics Genetics Clinics Database.