Genetic Testing for Breast Cancer: Who Needs It and Why

Here’s who may benefit (and who won’t).

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Part of the fear of breast cancer is simply not knowing if you’ll be one of the 12 percent of U.S. women who develops breast cancer over her lifetime. Some people have turned to genetic testing for breast cancer, hoping it could give them answers before cancer cells possibly arrive.

Is Breast Cancer Genetic?

“There’s only a small percentage of breast cancers that are diagnosed that we actually believe are genetically linked,” says Brenda Panzera, MD, an oncologist at Lenox Hill and Mount Sinai Hospitals in New York City. 

Like all risk factors for breast cancer, having certain genes does not cause breast cancer but instead can increases your risk. Genetic testing for breast cancer looks for gene mutations that are associated with breast cancer, namely the BRCA 1 gene and BRCA 2 gene.

The BRCA genes are associated with not only breast cancer, but also ovarian, fallopian tube, peritoneal, pancreatic, skin, and prostate cancers. While the average U.S. woman has a 12 percent chance of developing breast cancer, those with a BRCA gene mutation have a 45 to 65 percent chance, according to the Susan G. Komen Foundation.

Who Should Get Genetic Testing for Breast Cancer?

While genetic testing can’t tell you definitively whether you get have breast cancer in the future or not, it may be beneficial for some people. Knowing you have an increased risk of breast cancer can allow you to get screened more frequently and may help you recognize breast cancer symptoms more promptly. In some cases, women with very strong breast cancer risk factors may opt for preventive medication or surgery to further reduce their odds of getting breast cancer.

Doctors generally offer genetic testing for breast cancer to the following groups:

  • Women diagnosed with breast cancer under the age of 40

  • Women diagnosed with breast cancer and also have a first-degree relative with breast or ovarian cancer

  • Women who are diagnosed and are of Ashkenazi Jewish descent, in which the BRCA genes are more common

What Happens If You’re BRCA-Positive?

Since those with a BRCA gene mutation are at an increased risk, doctors will likely recommend more frequent screening.

“For women who are known to be BRCA-positive, we often will recommend that they have annual mammograms alternating with annual MRIs,” says Dr. Panzera, “so that they have breast imaging every six months.”

Clinical breast exams should also be done regularly throughout the year for women who test positively for the BRCA genes. While self-breast exams are a good tool, professionals may be more accurate and valuable for detecting breast cancer accurately.

Doctors also recommend regular ob-gyn exams for women with the BRCA genes, especially since this gene mutation increases the risk of ovarian and fallopian tube cancers.

“We sometimes discuss with patients who are known gene carriers the possibility of using … medications such as tamoxifen to decrease the risk of breast cancer,” says Dr. Panzera. Tamoxifen binds to estrogen receptors and blocks estrogen, according to the National Cancer Institute.

Another option is oral contraceptives, which has been linked to a lower risk of ovarian cancer. (Here are more things to know about the Pill.)

Beyond medication, women may choose to have prophylactic surgery—either a bilateral mastectomy to remove both breasts or a bilateral oophorectomy to remove the ovaries—before a cancer diagnosis. This greatly reduces the risk of cancer and may be an option for women with a very high risk of developing breast or ovarian cancer. (Learn more about the risk factors for breast cancer here.)

Genetic testing can never tell the whole story, but it can provide valuable information. Either way, it’s important to maintain regular appointments with your doctor. Find out what tests women need in their forties, and check out what tests women in their fifties need.