Genetic Testing for Breast Cancer

Early detection of breast cancer increases a woman’s treatment options and chances for survival. Genetic testing for breast cancer can alert women to an increased risk of the disease, allowing them to make lifestyle changes and take preventative measures.
 
The statistics for breast cancer are alarming: one out of every eight women in American will develop breast cancer at some point in their life. Over 192,000 new cases of breast cancer are reported every year.
 
Approximately five to ten percent of breast cancer cases are caused by inherited genetic abnormalities. Inherited changes to the genes BRCA1 and BRCA2 are known to greatly increase the risk of breast cancer and ovarian cancer. Both gene alterations can be detected with breast cancer genetic testing.
 
Several risk factors suggest the presence of alterations to BRCA1 and BRCA2. You might consider breast cancer genetic testing for these two genetic markers if you have any of the following:
  • a family history of ovarian cancer
  • a family history with more than one generation of breast cancer
  • a family member with bilateral breast cancer (cancer in both breasts)
  • a history of breast cancer in two or more family members
  • a male relative who has breast cancer
  • a personal history of breast cancer at a young age
  • a relative whose breast cancer genetic screening confirmed either BRCA1 or BRCA2
  • a relative with both ovarian and breast cancer
  • Ashkenazi (Eastern European) Jewish ancestry
  • breast cancer in a family member before the age of fifty.
BRCA1 and BRCA2 alternations can also affect men. Men who possess either alteration are more susceptible to breast cancer and prostate cancer.

Breast Cancer Genetic Testing

How is genetic testing done for breast cancer patients? The patient provides a blood sample which is delivered to the breast cancer genetic testing lab for analysis.
 
At the breast cancer genetic testing lab, the blood sample is examined for signs of alterations in BRCA1, BRCA2, and other genetic markers known to raise the risk of breast cancer. As medical research uncovers more inherited cancer risks, breast cancer genetic testing will expand to include new gene markers.
 
Genetic testing for breast cancer is a complex process that takes time: It can take several weeks for a breast cancer genetic testing lab to collect test results.

Interpreting Breast Cancer Genetic Testing Results

Here are some important facts to help you interpret the results of genetic testing for breast cancer correctly:
  • Approximately 10 percent of breast cancer genetic testing lab results indicate alterations in BRCA1 or BRCA2, but not the changes known to increase the risk of breast cancer. The effect of such changes to breast cancer risk is as yet unknown, but many genetic alterations are harmless.

  • Estimates vary, but the presence of either gene alteration increases the lifelong risk of breast cancer from 13 percent to between 60 and 80 percent.

  • If test results indicate your genetic profile does not include BRCA1 or BRCA2 alterations, this does not mean that you will not develop breast cancer. This test result shows that you have the same risk of the disease as the general female population: one in eight.

  • If the test does indicate the presence of BRCA1 or BRCA2 alterations, it doesn’t necessarily mean that you will develop breast cancer. The presence of these two markers does, however, mean you are in a higher risk group for breast cancer.

Breast Cancer Genetic Testing and You

The results of genetic testing for breast cancer should be discussed with your family doctor. A number of options are available if your risk of breast cancer is high. Choices range from careful observation of breast changes to precautionary mastectomies (surgical removal of the breasts).
 
The limits and benefits of each response need to be carefully weighed. It is possible to have a double mastectomy and still develop breast cancer, as the surgery does not removal all breast tissue.
 
Fortunately, genetic research increases our knowledge of breast cancer every year. It may one day be possible to treat inherited breast cancer through gene therapy, effectively repairing the alterations that cause breast cancer. Until then, genetic testing for breast cancer can help women make important decisions about their health.
 
Resources
 
Mayo Foundation for Medical Education and Research (2008). Genetic testing for breast cancer: Who’s it for? Retrieved November 10, 2008, from the Mayo Clinic Web site: http://www.mayoclinic.com/health/genetic-testing-for-breast-cancer/HQ00350.
 
National Cancer Institute (n.d.). Genetic testing for BRCA1 and BRCA2: It’s your choice. Retrieved November 10, 2008, from the National Cancer Institute Web site: http://www.cancer.gov/cancertopics/factsheet/risk/brca.
 
National Office of Public Health Genomics (2007). Fact sheet on genetic testing for breast and ovarian cancer susceptibility. Retrieved November 10, 2008, from the National Office of Public Health Genomics Web site: http://www.cdc.gov/genomics/training/perspectives/factshts/breastcancer.htm.