The genetic mutations that can increase breast cancer risk, including mutations in the BRCA1, BRCA2, and PALB2 genes, are the same for both black and white women, which means that currently available genetic tests are effective for black women, according to a study.
The research was published online on May 19, 2020, by the Journal of the National Cancer Institute. Read the abstract of “Contribution of Germline Predisposition Gene Mutations to Breast Cancer Risk in African American Women.”
Genetic mutations linked to breast cancer
A germline variant is a change, or mutation, in a gene that is inherited from your parents and is in all your DNA.
Three of the most well-known genes that can mutate and raise the risk of breast and/or ovarian cancer are BRCA1, BRCA2, and PALB2. Women who inherit a harmful mutation, or abnormal change, in any 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. Many inherited cases of breast cancer have been associated with mutations in these three genes.
The function of the BRCA and PALB2 genes is to keep breast cells growing normally and prevent any cancer cell growth. But when these genes contain mutations that are passed from generation to generation, they do not function normally and breast cancer risk increases. Abnormal BRCA1, BRCA2, and PALB2 genes may account for up to 10% of all breast cancers, or 1 out of every 10 cases.
About this study
Earlier studies looking at the genetic mutations linked to a higher risk of breast cancer included mainly white women, so it has been unclear if the same genetic mutations increased breast cancer risk by the same amount in black women.
Earlier research studies looking at genetic mutations linked to breast cancer in black women were very small, so the researchers could only conclude that mutations in the BRCA1 and BRCA2 genes were linked to a higher risk of breast cancer in black women.
So the researchers who did this study were concerned that current genetic tests might not be looking for the correct mutations linked to a higher risk of breast cancer in black women.
The study included 5,054 black women who had been diagnosed with breast cancer and 4,993 black women of the same ages who had not been diagnosed with breast cancer.
All the women had genetic testing that looked for mutations in 23 genes known to be linked to a higher risk of cancer.
Harmful mutations were found in:
- 10.3% of women diagnosed with estrogen-receptor-negative breast cancer
- 5.2% of women diagnosed with estrogen-receptor-positive breast cancer
- 2.3% of women who had not been diagnosed with breast cancer
Mutations in the BRCA1, BRCA2, and PALB2 genes were linked to a high risk of breast cancer.
Mutations in the RAD51D gene were linked to a high risk of estrogen-receptor-negative breast cancer.
Mutations in the CHEK2, ATM, ERCC3, and FANCC genes were linked to a moderate risk of estrogen-receptor-positive breast cancer.
Mutations in the RECQL gene were linked to a moderate risk of all types of breast cancer.
"This means that the [genetic tests] 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," said lead author Julie Palmer, Karin Grunebaum Professor in Cancer Research at the Boston University School of Medicine.
What this means for you
If you are a black woman who has been diagnosed with breast cancer or who hasn’t been diagnosed but you have a strong family history of the disease, this study offers reassurance that current genetic tests will accurately find any mutations linked to a higher risk of breast cancer.
Statistics show that rates of genetic testing are much lower in black women diagnosed with breast cancer than in white women diagnosed with breast cancer.
In February 2019, the American Society of Breast Surgeons issued updated guidelines saying that genetic testing should be made available to everyone who has been diagnosed with breast cancer.
There are a number of reasons why someone diagnosed with breast cancer or who is at high risk because of family history might want to consider genetic testing:
- Women who have a BRCA1 or BRCA2 mutation can benefit from a class of medicines called PARP inhibitors. Two PARP inhibitors are approved to treat BRCA1- and BRCA2-associated metastatic breast cancer.
- Anyone with a genetic mutation linked to breast cancer has a higher risk of a second cancer, so more frequent screening is usually recommended.
- If a person has a genetic mutation, every first-degree relative — sisters, brothers, sons, and daughters — has a 50% risk of having the same mutation. Having this knowledge can allow for enhanced screening and prevention steps for loved ones who also may have the mutation.
- If you haven’t been diagnosed but do test positive for a genetic mutation, there are steps you can take to reduce your risk of breast cancer, including:
- a more aggressive screening plan that starts at an earlier age
- taking hormonal therapy medicine to block the effect of estrogen on breast tissue or reduce the amount of estrogen in the body
- removing the healthy breasts (prophylactic mastectomy)
- removing the healthy ovaries (prophylactic oophorectomy)
If you’ve been diagnosed with breast cancer or are at high risk because of family history, you may want to talk to your doctor or a licensed certified genetic counselor about your diagnosis and/or your family history and ask if having a genetic test makes sense for you. A licensed certified genetic counselor or your doctor can help you understand the test and accurately interpret the results.
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