BRCA 1 & 2: The "Breast-Cancer Genes"

We hear a lot about women that are genetically prone to breast and ovarian cancer, but what does that mean?

BRCA 1 and BRCA 2 are human genes that belong to a class of genes known as tumor suppressors. In normal cells, these genes help prevent uncontrolled cell growth. But if these genes happen to mutate or change, they can increase one's risk of developing hereditary breast and ovarian cancer.

What happens if a woman inherits a mutated BRCA 1 or 2 gene?

Women with either of these gene mutations have a greatly increased lifetime risk of developing breast and/or ovarian cancer at a younger age. Those with BRCA 1 mutations also have an increased risk of developing

  • cervical cancer
  • uterine cancer
  • pancreatic cancer
  • colon cancer

Those with BRCA 2 mutations have an increased risk of melanoma, a serious skin cancer, as well as cancer of the

  • pancreas
  • stomach
  • gallbladder
  • bile duct

Remember: “Increased Risk” Is Not a Guarantee

First, let’s back up for a moment and get something straight. Having one of these mutations does not mean that a woman will actually develop any of these cancers. Lifetime breast-cancer risk in the general population is 12 percent of women, compared to about 60 percent for women with a BRCA 1 or 2 mutation. Lifetime ovarian-cancer risk, for example, is 1.4 percent in the general population, compared to anywhere from 15 percent to 40 percent in those with a mutation.

Who is at most at risk of a genetic mutation?

These mutations are most commonly seen in families with

  • a history of multiple cases of breast cancer
  • a history of both breast and ovarian cancers
  • one or more family members with two primary cancers (that is, original tumors that develop in different parts of the body)
  • an Ashkenazi Jewish background

Is there a test for these gene mutations?

If you believe that you are at risk of a BRCA mutation, you can have a blood test to determine if you are carrying the genetic mutation. But first, healthcare professionals recommend that you undergo genetic counseling both before and after this type of testing. Why? Because an experienced genetic counselor will be able to identify how serious your risks are, explain the results of your test, define the psychological risks and benefits of knowing your status, and discuss with you the risk of the mutation to your children.

What are the options if a test shows that you have a genetic mutation?

Several options are available for addressing the cancer risk of someone who is carrying a BRCA 1 or 2.

  • Surveillance. Cancer screening such as mammography, breast MRIs, clinical breast exams, and pelvic exams, as well as monitoring for ovarian tumor markers
  • Prophylactic surgery. Removing the breast, ovaries, and fallopian tubes will lower the cancer risk significantly. Such surgeries can never completely eliminate all risk, however, since women may still develop cancer of the peritoneal surfaces (lining of the abdomen)
  • Risk avoidance. Women at high risk can of course still follow the standard directives for cutting their cancer risks: Avoiding exposure to exogenous estrogen, maintaining a healthy weight, increasing exercise, decreasing or avoiding alcohol, and maintaining a low-fat diet.
  • Chemoprevention. Some medications have been shown to decrease the risk of breast cancer, including tamoxifen and raloxifene. These may be used in high-risk populations to prevent breast cancer.

What if you think you are at risk of having a BRCA 1 or 2 mutation?

If you think you may be at risk of a genetic mutation, see your healthcare provider to discuss your concerns. If you agree that you would like to proceed with testing, your healthcare provider can refer you for genetic counseling and testing.

©1996-2012, Johns Hopkins University. All rights reserved. Disclosure: The information provided here is compiled by The Johns Hopkins University School of Medicine with editorial supervision by one or more of the members of the faculty of the School of Medicine pursuant to a license agreement with Yahoo! Inc. under which the School of Medicine and its faculty editors receive licensing fees and payment for services rendered within the scope of the License Agreement. Johns Hopkins subscribes to the HONcode principles of the Health on the Net Foundation.

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