Guide to BRCA Genes & Breast Cancer

This article explains what is known about the BRCA genes, their connection to cancer, and how to get tested.

About BRCA Genes  |  Risk Factors  |  Genetics  |  Results  |  Next Steps

Key Info

  • Mutations in BRCA1 and BRCA2 genes have been linked to an extremely high lifetime risk of developing breast and/or ovarian cancer.
  • Each child of a parent with a BRCA mutation has a 50 percent chance of inheriting it.
  • Tests are available to determine if you are predisposed to BRCA1 and/or BRCA2 mutations.

What Are BRCA Genes?

BRCA genes are human tumor suppressor genes. They produce proteins that repair damaged DNA, helping to ensure the stability of a cell’s genetic material.

BRCA genes were first discovered in 1990. The two BRCA types — BRCA1 and BRCA2 — are unrelated except for the fact that both are active in breast and other tissue. The name “BRCA” is an abbreviation for “breast cancer.”

BRCA Genes and the Risk of Cancer

When functioning normally, BRCA genes help fight cancer. However, when they carry specific mutations that prevent them from functioning properly, BRCA1 and BRCA2 genes have been associated with an increased risk of developing breast and ovarian cancers.

Risk Factors

Mutations in BRCA genes can be inherited or can arise spontaneously. If a parent has a BRCA mutation, then each of their children will have a 50 percent chance of inheriting it.

BRCA mutations are also more common in certain ethnic populations. For instance, Ashkenazi Jewish people have a greater chance of developing harmful BRCA mutations than the general population.

Size of Increase

A recent large study of BRCA1 and BRCA2 female carriers determined the following:

  • Breast Cancer: About 72 percent of women with harmful BRCA1 mutations and 69 percent of women with harmful BRCA2 mutations will develop breast cancer.
  • Ovarian Cancer: About 44 percent of women with harmful BRCA1 mutations and 17 percent of women with harmful BRCA2 mutations will develop ovarian cancer.

In contrast, only 12 percent of women without harmful BRCA mutations develop breast cancer, while only about 1 percent develop ovarian cancer.

Genetic Tests for BRCA Mutations

There are several different types of tests available for determining whether you are predisposed to BRCA1 and/or BRCA2 mutations.

  • Comprehensive Testing: This looks for possible mutations across the entire length of the BRCA1 and BRCA2 genes.
  • Single Site Testing: This searches for a specific mutation type after a hereditary mutation has been identified.
  • Multisite Testing: This searches for three specific gene changes common to Ashkenazi Jewish ancestry.

BRCA Genetic Test Results

BRCA genetic tests can produce three types of results: positive, negative, or uncertain.

Positive Result

A positive result means a BRCA1 or BRCA2 mutation has been found. This is associated with a much higher risk of developing breast or ovarian cancer. But it’s important to note that a positive result does not predict when or whether you will develop cancer.

If you get a positive result, you should consider taking the following measures:

  • More Frequent Screening: Scheduling clinical breast exams every six months, as well as mammograms and/or MRIs every year, can help detect signs of breast cancer early.
  • Preventive Medication: Studies have shown that Tamoxifen reduces the risk of breast cancer by about 50 percent for women with BRCA mutations. Other medications include raloxifene, exemestane, and anastrozole.
  • Preventive Surgery: Also called prophylactic surgery, this involves removing breast tissue, fallopian tubes, and/or ovaries before any signs of cancer have been detected.

Negative Result

A negative result means no BRCA1 or BRCA2 mutation has been found. However, depending on your family history, this result can still be interpreted several different ways.

If you have a close relative who is known to carry a specific BRCA mutation, the negative test is considered a “true negative.” This means your relative’s harmful BRCA mutation is not present, giving you the same risk of cancer as the general population.

If your family history suggests the possibility of a harmful BRCA mutation, but the specific type is not known, then the negative result is less conclusive. New BRCA mutations are still being discovered, which means that it’s possible for you to have a negative test result but still carry a harmful mutation.

Uncertain Result

An uncertain result means a BRCA1 or BRCA2 mutation has been found that has not previously been associated with cancer. About 10 percent of women receive this type of result.

As scientists conduct more research, they will gain a better understanding of the different BRCA mutations. Until then, it’s important to speak with a doctor or genetic counselor about how an uncertain result affects your risk of cancer.

Next Steps

If you need help understanding BRCA genes and your breast cancer risks, we’re here for you. Call us now at (212) 305-9676 or fill out our online appointment request form.

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