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What are the BRCA1 and BRCA2 genes?

Jay Harness

Everyone has the BRCA1 and BRCA2 genes, but certain changes in genes — changes called mutations — can lead to an increased risk of breast cancer and other cancers.

Woman having a discussion with doctor

This past spring, Angelina Jolie announced that she’d had both of her breasts removed as a preventive measure against breast cancer. She did it after testing positive for a BRCA1 gene mutation. She also has a family history of cancer, having lost her mother to ovarian cancer and her aunt to breast cancer.

A woman with a BRCA1 mutation has a 65 to 85 percent risk of getting breast cancer during her lifetime. In Angelina Jolie’s case, her doctors estimated her risk was even higher: 87 percent.

In addition to breast cancer, women with the BRCA1 gene mutation have an increased risk of developing ovarian cancer (25 to 40 percent). Women with BRCA2 mutations have a 65 to 85 percent lifetime risk of getting breast cancer, an increased risk of getting ovarian cancer and an increased risk of other cancers such as pancreatic cancer and stomach cancer.

How do I know if I have these gene mutations?

The only sure-fire way to know if you have the gene mutations is to take a genetic test. However, there are some trademark signs that you may have the mutations, based on your family history:

  • A family history of breast cancer that develops before age 50
  • A family history of breast and/or ovarian cancer
  • A family history of male breast cancer
  • Ashkenazi Jewish ancestry

Is it possible to get breast cancer if I don’t have these gene mutations?

Yes, it is still possible to get breast cancer without these gene mutations. There are other genes or mutations and several other risk factors that may come into play to cause breast cancer. The BRCA1 and BRCA2 genes are just the most common genetic mutations that lead to breast cancer. If you have a family history of breast cancer, even without the BRCA1 and BRCA2 mutations, you may have an increased risk of getting breast cancer.

Why do women have mastectomies before getting breast cancer?

The idea of a preventive mastectomy is that if you remove most of a woman’s breast tissue, the likelihood of the remaining breast tissue becoming cancerous decreases dramatically. In Angelina Jolie’s case, her breast cancer risk went from 87 percent to less than 5 percent.

What should I do if I think I may have these gene mutations?

Make sure your doctor knows your family history of disease. It may be worthwhile to speak with a genetic counselor and get tested for the BRCA1 and BRCA2 mutations. Not everyone who has the gene mutation decides to take preventive measures like a double mastectomy, but many do.

Ultimately, it is your decision to be tested for the gene mutation or not. The test is a simple mouth swab or blood test. Knowing that you have the gene mutation could lead to a lot of new choices and medical options, but finding out that you don’t have the gene mutation doesn’t rule out the possibility that you may get breast cancer.

Dr. Harness is the medical director of Breast Cancer Answers and the past president of the American Society of Breast Surgeons.

More on breast cancer detection and prevention

The scary truth about dense breast tissue
How frequently should you screen?
Quick guide to breast cancer screening

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