Breast Cancer Education: Genetic Testing

Family history and some inherited genetic mutations affect breast cancer risk in both men and women. Having an immediate family member (a parent, sibling or child) with a history of breast cancer increases your own risk of breast cancer. You should know, however, that genetic mutations linked to breast cancer are rare. Not all men and women with a family history of breast cancer are likely to have a genetic mutation. Only five to 10 percent of breast cancers in the U.S. are linked to an inherited genetic mutation.

Mutations are changes in the genetic code of a gene that affect its function. Inherited gene mutations can be passed on from a parent to a child. Some inherited gene mutations increase breast cancer risk. Genetic testing gives people the chance to learn if their family history of breast cancer is likely due to an inherited gene mutation.

BRCA1 and BRCA2 (BReast CAncer genes 1 and 2) are the best-known genes linked to breast cancer.

People who have a BRCA1 or BRCA2 mutation have a greatly increased risk of breast cancer and (for women) ovarian cancer. Although genetic testing for BRCA1 and BRCA2 is widely advertised, testing is only recommended for certain people, including those with:

• A personal history of breast cancer at age 50 or younger
• A personal history of triple negative breast cancer (breast cancer that is estrogen receptor-negative, progesterone receptor-negative and HER2/neu receptor-negative)
• A personal or family history of male breast cancer
• A personal or family history of bilateral breast cancer (cancer in both breasts)
• A personal history of ovarian cancer
• A parent, sibling, child, grandparent, grandchild, uncle, aunt, nephew, niece or first cousin diagnosed with breast cancer at age 45 or younger
• A mother, sister, daughter, grandmother, granddaughter, aunt, niece or first cousin diagnosed with ovarian cancer
• A family history of both breast and ovarian cancers on the same side of the family (either mother's or father's side of the family)
• Ashkenazi Jewish heritage and a family history of breast or ovarian cancer

There is only a very small chance that your family carries a BRCA1/2 mutation if:

• You or an immediate family member is the only person in your family with breast cancer
• The breast cancers in your family all occurred at older ages

In most cases, genetic testing is not recommended when there is a low chance of finding a mutation. Remember that most breast cancers are not due to a BRCA1/2 mutation. Although BRCA1/2 testing is a simple blood test, the risks and benefits should be considered before testing. There are potential physical, emotional and financial impacts of knowing your genetic status. Thus, testing for the BRCA1/2 mutation is recommended only for people who fall into one of the categories listed above.

A health care provider or genetic counselor can talk with you about genetic testing issues. For more information on genetic counseling, visit the National Cancer Institute’s website (or call its hotline at 1-800-4-CANCER) or visit the National Society of Genetic Counselors’ website.

For more information on inherited gene mutations, visit: http://ww5.komen.org/BreastCancer/

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