The BRCA Gene Mutation and Breast Cancer Risk

About 1 in 8 women will be diagnosed with breast cancer at some point. And the risk is higher for those with a BRCA gene mutation -- about 7 in 10 women who have it will be diagnosed with breast cancer by age 80. But there are a lot of things that affect your odds, and having a BRCA gene mutation doesn’t guarantee you’ll get the disease. It’s important to work with your health care team to understand what it means for you.

What Is the BRCA Gene?

“BRCA” is short for “breast cancer gene,” and there are two types: BRCA1 and BRCA2. Everyone has both types, and they’re actually helpful. They fix DNA damage that can lead to cancers and tumors. They also make proteins that help stop tumors from growing.

But some people have a different form of the gene known as a mutation. So it may not be able to ward off breast cancer like regular BRCA genes would. About 1 in 400 people have mutated BRCA genes. Women with a BRCA1 mutation have a 72% chance of being diagnosed with breast cancer by age 80, and women with a BRCA2 mutation have a 69% chance. Men with a BRCA mutation are also at a higher risk of breast cancer.

Risk of Other Cancers

You’re also more likely to get ovarian cancer if you have a BRCA gene mutation. Women with a BRCA1 mutation have a 44% chance, and women with a BRCA2 mutation have a 17% chance, compared to a rate of 1.3% in those who don’t have the gene mutation.

BRCA gene mutations also raise the risk of fallopian tube cancer and peritoneal cancer. Men face a higher risk of prostate cancer, and both men and women are at a higher risk of pancreatic cancer. If you have a BRCA gene mutation, you also have higher odds of getting cancer in your other breast.

It’s impossible to know if you have the mutation without gene testing. But if you have a parent with a mutated BRCA gene, there’s a 50% chance you have it, too. A blood or saliva test can show if you have it. Doctors only offer the test to people at risk because of medical or family history, or because of the type of breast cancer they have.

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Who Should Get the Test?

You don’t have to do BRCA gene testing. But if you’re thinking about it, you may be able to get it if:

  • You were diagnosed with breast cancer before menopause or before age 50.
  • You were diagnosed with triple-negative breast cancer at 60 or younger.
  • You’ve had breast cancer that affected both breasts (bilateral breast cancer).
  • You have a family member with bilateral breast cancer.
  • You’ve been diagnosed with breast and ovarian cancers.
  • You have a family member with both breast and ovarian cancers.
  • You’ve been diagnosed with ovarian cancer.
  • You have a relative with ovarian cancer.
  • You’ve been diagnosed with breast cancer and have one or more relatives with breast cancer at age 50 or younger, a relative with ovarian cancer, or two or more relatives with breast or pancreatic cancer.
  • Two or more close relatives (parents, siblings, children) were diagnosed with breast cancer at a young age.
  • A male relative was diagnosed with breast cancer.
  • You have a relative with a known BRCA1 or BRCA2 mutation.
  • You are of Ashkenazi Jewish descent, with a close relative who has breast, ovarian, or pancreatic cancer.

What Do the Test Results Mean?

If you’re thinking about getting genetic testing, experts say you should get genetic counseling first. This can help you understand your risk, what the test will or won’t show, and what it all means.

If your test shows you have a BRCA mutation, your doctor will talk to you about your options and risk. This means you have a 50% chance of passing the gene to a child, and there’s a 50% chance your brothers or sisters have it, too. They can get tested, or they can talk to a genetics counselor first.

A negative test result -- meaning no BRCA mutation -- can be tricky. If a close relative has or had a known BRCA gene mutation and your results don’t show it, that’s called a true negative. This means you don’t have the gene and there’s no chance you can pass it on to your children. Your breast cancer risk is the same as everyone else.

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If your family history suggests a BRCA gene mutation but no one's tests found it, it’s possible the test missed the gene mutation. But the chances of that are very low. Scientists are also finding new BRCA1 and BRCA2 gene mutations, so that’s another reason a test could miss it.

In some cases, gene testing can show other changes in the BRCA1 or BRCA2 genes that haven’t been linked to cancer. Your doctor may call this an “ambiguous” result because no one knows if that specific mutation can affect your health.

What Happens if I Have It?

If you have a BRCA1 or BRCA2 gene mutation, there are a few things you can do to manage your cancer risk.

Get regular screening tests for breast cancer, including breast exams, mammograms, and MRIs, starting at an earlier age (25 to 35) than most people do. Get to know how your breasts look and feel. If you notice any changes, see your doctor ASAP. And talk with your doctor about blood tests, pelvic exams, and transvaginal ultrasound to look for ovarian cancer.

Some women choose to have a double mastectomy -- surgery to remove both breasts -- to lower their chances of getting cancer. It’s also possible to have your ovaries and fallopian tubes taken out. This doesn’t get rid of all risk, but it does significantly lower it.

The drug tamoxifen may be an option. It lowers the chances of being diagnosed with breast cancer by half if you already have a higher risk. Birth control pills may lower the risk of ovarian cancer in any woman and those with BRCA gene mutations, though hormonal birth control can slightly raise your risk of breast cancer.

Be sure to talk to your doctor about all your options. Together, you can make the best decision for your health.

WebMD Medical Reference Reviewed by Laura J. Martin, MD on September 09, 2019

Sources

SOURCES:

American Cancer Society: “Can Ovarian Cancer Be Prevented?” “American Cancer Society Recommendations for the Early Detection of Breast Cancer.”

Breastcancer.org: “Risk of Developing Breast Cancer.”

Mayo Clinic: “BRCA gene test for breast and ovarian cancer risk.”

National Breast Cancer Foundation: “BRCA: The Breast Cancer Gene.”

National Cancer Institute: “BRCA Mutations: Cancer Risk and Genetic Testing.”

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